Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH

Narayanasamy Rajendiran; Ayyadurai Mani; Palanichamy Ramasamy; Sengamalai Senthilmurugan

doi:doi:10.11648/j.ajn.20261002.11

Research Article |

| Peer-Reviewed

Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH

Narayanasamy Rajendiran^*

, Ayyadurai Mani

, Palanichamy Ramasamy

, Sengamalai Senthilmurugan

Published in American Journal of Nanosciences (Volume 10, Issue 2)

Received: 11 March 2026 Accepted: 23 March 2026 Published: 13 April 2026

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Abstract

The spectral properties of the silver–3-anisidine–cyclodextrin (Ag: 3AS: CD) inclusion complex nanomaterials in solution were investigated using UV–visible, steady-state fluorescence, time-resolved fluorescence, SEM, DSC, FTIR, XRD, ¹H NMR, and molecular modeling methods. The distinct spectral changes observed for 3AS upon the addition of CDs at different pH values indicate that the geometries of the resulting inclusion complexes vary with pH. While 3AS exhibits a single emission maximum in solvents and in α-CD, a dual emission is observed in β-CD. The lifetimes of the inclusion complexes were longer than that of the free 3AS molecule. The relatively narrow cavity of α-CD likely restricts the free rotation of the amino or methoxy groups of 3AS, inhibiting ICT-state formation and thereby enhancing the normal emission. The calculated HOMO–LUMO energy gap, total energy, free energy, enthalpy, entropy, dipole moment, and zero-point vibrational energy of the CD: 3AS complex differed significantly from those of the isolated 3AS, α-CD and β-CD molecules, and both the vertical and horizontal bond lengths between the amino and methoxy groups are smaller than the β-CD cavity size confirming the formation of an inclusion complex. SEM images and EDX analysis confirm the presence of silver in the Ag: 3AS: β-CD nanomaterials. In the FTIR spectra, most characteristic peaks diminish or disappear, accompanied by a marked decrease in intensity for the Ag: 3AS: CD nanocomplexes, suggesting strong interactions between 3AS and nano silver. The ¹H NMR chemical shifts of 3AS protons move both upfield and downfield indicating restricted mobility and strong host–guest interactions within the nano Ag–CD matrix.

Published in	American Journal of Nanosciences (Volume 10, Issue 2)
DOI	10.11648/j.ajn.20261002.11
Page(s)	41-51
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

3-Anisidine, Cyclodextrin, Silver Nano, Inclusion Complex, Nanomaterials

1. Introduction

Because of their well-defined torus-like structure, hydrophobic inner cavity, and hydrophilic external hydroxyl rims, cyclodextrins (CDs) are capable of forming inclusion complexes with a wide range of guest molecules

[1-5]

. This encapsulation ability underlies their extensive use in analytical chemistry, separation science, and pharmaceutical applications. CD chemistry continues to attract significant interest not only because of its relevance to pharmaceutical science and technology, but also because CD inclusion provides an excellent model for mimicking enzyme–substrate interactions

[6-10]

. Moreover, studies of host–guest interactions in CD systems offer valuable insights into the nature of hydrophobic and hydrophilic forces.

Our earlier investigations on various aromatic systems

[11-15]

have demonstrated the occurrence of photophysical processes such as intramolecular charge transfer (ICT), intramolecular proton transfer (IPT), and excimer formation in CD media. CDs are particularly suitable for such studies because their non-polar cavities can encapsulate organic solutes of appropriate size in aqueous solutions. In continuation of this work, the present study focuses on: (i) the absorption and fluorescence spectral shifts and the first excited singlet-state lifetime of 3-anisidine (3AS) in α-CD, β-CD, solvents of varying polarity, and at different pH values; (ii) the proton-transfer behavior of 3AS in aqueous, α-CD, and β-CD media; (iii) the structures and geometries of the resulting inclusion complexes using PM3 molecular modeling; and (iv) the doping effect of 3AS: CD on silver nanomaterials, characterized by DSC, FTIR, ¹H NMR, and SEM analyses.

2. Experimental

2.1. Preparation of CD Solution

The concentration of the 3AS stock solution was 2 × 10^-2 M. An aliquot of 0.2 mL of this stock was transferred into a 10 mL volumetric flask, followed by the addition of α-CD or β-CD solutions at varying concentrations (0.2, 0.4, 0.6, 0.8, and 1.0 × 10^-2 M). Each mixture was diluted to the mark with triply distilled water and shaken thoroughly. The final concentration of 3AS in all flasks was maintained at 4 × 10^-4 M. All measurements were performed at room temperature (298 K).

2.2. Preparation of Ag: 3AS: CD Nanomaterials

A 0.01 M silver nitrate solution was prepared in 50 mL of deionized water and warmed to 50–60°C for 30 minutes. To this, 1–2 mL of 1% trisodium citrate solution (1 g in 100 mL deionized water) was added with vigorous shaking. The appearance of a pale yellow color indicated the formation of silver nanoparticles

[26-30]

. Yield is 60%. The particles are washed with alcohol.

For preparing the Ag: 3AS: CD nanocomplex, CD (1 mmol) was dissolved in 40 mL of distilled water, and 3AS (1 mmol) dissolved in 10 mL ethanol was added slowly with continuous stirring. The mixture was stirred at 50°C for 2 hours using a magnetic stirrer. The freshly prepared silver nanoparticle solution was then added and stirring was continued for an additional 2 hours. The resulting mixture was gently warmed at 40–50°C until the volume was reduced by approximately 50%.

The concentrated solution was refrigerated overnight at 5°C. The precipitated Ag–3AS–CD nanomaterials were collected by filtration and washed with small quantities of ethanol and water to remove uncomplexed 3AS, Ag, and CD. The final product was dried under vacuum at room temperature and stored in an airtight container. The powdered samples were used for subsequent analyses

[21-25]

3. Result and Discussion

3.1. Absorption and Fluorescence Spectral Results

Table 1 and Figures 1 and 2 present the absorption, emission, and time-resolved fluorescence values of 3-anisidine (3AS) (2 × 10^-4 M) in pH ~2, pH ~7, and pH ~11 solutions containing varying concentrations of α-CD and β-CD. To compare the inclusion behavior of the neutral and monocationic forms of 3AS, complexation studies were carried out at different pH values. In CD-free solutions, 3AS exhibits the following spectral characteristics: pH ~2: λ_abs = 270, 218 nm; λ_flu= 297 nm, pH ~7: λ_abs = 282, 230, 215 nm; λ_flu = 336, 297 (shoulder) nm, pH ~11: λ_abs = 282, 230, 212 nm; λ_flu = 337 nm. These results indicate that neutral 3AS predominates at pH ~7 and pH ~11, while the blue-shifted absorption bands in pH ~2 reflect the presence of the monocationic species. The emission maximum at 336 nm in pH ~7 resembles spectra in non-aqueous solvents and is therefore assigned to the molecular form of 3AS.

In both the absence and presence of α-CD and β-CD, pH strongly influences the absorption and emission spectral features of 3AS. In α-CD, no significant absorption shift is observed at any pH. In β-CD, the absorption spectra remain unchanged in pH ~2 and pH ~11, whereas at pH ~7, the absorption maximum exhibits a blue shift from 282 to 272 nm. In all pH conditions, the absorbance of 3AS decreases with increasing CD concentration.

In aqueous CD-free solutions, the emission maxima at pH ~7 and pH ~11 are identical, but differ from that at pH ~2. In α-CD, the emission maximum appears at 297 nm in pH ~2 and at 337 nm in pH ~7 and pH ~11. Increasing α-CD concentration decreases emission intensity at pH ~2 but enhances it at pH ~7 and pH ~11. In β-CD, increasing concentration diminishes the shorter-wavelength (SW, normal) emission but enhances the longer-wavelength (LW, ICT) emission in all pH conditions. The SW band is red-shifted in pH ~7 and blue-shifted in pH ~11. At pH ~7, α-CD and β-CD produce single-band emission, whereas at pH ~2 dual emissions are observed. At pH ~11, α-CD produces a single emission band, while β-CD yields dual emission.

In the excited state, emission intensities increase markedly with α-CD concentration in pH ~7 and pH ~11, but decrease with increasing β-CD concentration. At pH ~2, emission intensities decrease in both CDs. In CD-free pH ~7 and pH ~11 solutions, the LW (ICT) band is weak; however, its intensity increases significantly with β-CD concentration but does not appear in α-CD solutions.

Table 1. Absorption and fluorescence maxima of 3-Anisidine (3AS) with different α-CD and β-CD concentrations.

Concentration of α-CD x10^-3M	pH - 2				pH - 7				pH - 11
Concentration of α-CD x10^-3M	_abs	log 	_flu	τ	_abs	log 	_flu	τ	_abs	log 	_flu	τ
3AS only (without CD)	270 219	3.24	297	0.34	282 230 215	3.23	336 297sh	0.35	282 231 215	3.23	337	0.24
0.2 M α-CD	270 219	3.23	297	0.41	282 230 215	3.22	338 297sh	0.43	282 231 215	3.21	337	0.28
1.0 M α-CD	270 219	3.17	298	0.50	282 230 215	3.17	338 297sh	0.53	282 231 215	3.17	337 435	0.32
K (1: 1) x10⁵M^-1	56		356		62		367		74		451
G (kcalmol^-1)	-10.1		-14.7		-10.3		-14.8		-10.8		-15.4
0.2 β-CD	270 218	3.17	298	0.43	279 230 213	3.20	435 333 297sh	0.46	282 230 213	3.20	339	0.31
1.0 β-CD	270 220	3.08	304	0.55	272 230 220	2.96	442 332 297sh	0.57 0.27	282 230 217	3.18	356 438	0.34 0.22
Excitation wavelength (nm)			260				260				280
K (1: 1) x10⁵M^-1	85		416		104		428		112		514
G (kcalmol^-1)	-11.1		-15.1		-11.7		-15.2		-11.8		-15.7

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Figure 1. Absorbance spectra of 3AS in different α-CD and β-CD concentrations (M): (1) 0, (2) 0.002, (3) 0.004, (4) 0.006, (5) 0.008 and (6) 0.01.

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Figure 2. Fluorescence spectra of 3AS in different α-CD and β-CD concentrations (M): (1) 0, (2) 0.002, (3) 0.004, (4) 0.006, (5) 0.008 and (6) 0.01.

The presence of isosbestic points in the absorption spectra at all pH values suggests the formation of a 1: 1 inclusion complex, although the guest orientation may vary

[16]	N.Rajendiran,T.Mohandoss, G.Venkatesh, Investigation of inclusion complexes of sulfamerazine with α- and β-cyclodextrins: An experimental and theoretical study, Spectrochimica Acta A, 124(2014) 441-450. https://doi.org/10.1016/j.saa.2014.01.018 View Article
[17]	G.Venkatesh, A. Antony Muthu Prabhu, N.Rajendiran, Azonium-Ammonium Tautomerism and Inclusion Complexation of 1-(2,4-diamino phenylazo) naphthalene and 4-Amino azobenzene, J.Fluorescence, 21(2011) 1485-1497. https://doi.org/10.1007/s10895-011-0863-5 View Article
[18]	G.Venkatesh, R. K.Sankara narayanan, A. Antony Muthu Prabhu, N.Rajendiran, Absorption and fluorescence spectral characteristics of norepinephrine, epinephrine, isoprenaline, methyldopa, terbutaline and orciprenaline drugs, Physics and Chemistry of Liquids, 50(2012) 434-452. https://doi.org/10.1080/00319104.2011.589376 View Article
[19]	T.Stalin, R.Anithadevi, N.Rajendiran, Spectral characteristics of ortho, meta and para-dihydroxybenzenes in different solvents, pH and β-CD. Spectrochimica Acta, 61A (2005) 2495-2504. https://doi.org/10.1016/j.saa.2004.12.031 View Article
[20]	T.Stalin, P. Vasantharani, B.Shanthi, A.Sekar, N.Rajendiran, Inclusion complex of 1,2,3-trihydroxybenzene with α- and β-cyclodextrins, Indian J Chemistry, 45A (2006) 1113-1120.
[21]	K.Sivakumar, T.Stalin, N.Rajendiran, Dual fluorescence of diphenyl carbazide and benzanilide: Effect of solvents and pH on electronic spectra, Spectrochimica Acta, 62A (2005) 991-999. https://doi.org/10.1016/j.saa.2005.02.011 View Article
[22]	J.Prema Kumari, A. Antony Muthu Prabhu, G. Venkatesh, V. K. Subramanian, N.Rajendiran, Effect of solvents and pH on β-CD Inclusion complexation of 2,4-dihydroxyazobenzene and 4-hydroxy azobenzene, J.Solution Chemistry, 40(2011) 327-347. https://doi.org/10.1007/s10953-011-9654-7 View Article
[23]	J. Thulasidhasan, N. Rajendiran, Host-guest inclusion complexes of propafenone hydrochloride with α- and β-cyclodextrins: Spectral and molecular modeling study, Spectrochim Acta, 115A (2013) 559-567. https://doi.org/10.1016/j.saa.2013.06.066 View Article
[24]	J.Prema Kumari, A. Antony Muthu Prabhu, G.Venkatesh, V. K.Subramanian, N. Rajendiran, Spectral characteristics of sulfadiazine, sulfisomidine: Effect of solvents, pH and β-CD, Physics and Chemistry of Liquids, 49(2011) 108-132. https://doi.org/10.1080/00319100903563634 View Article
[25]	N.Rajendiran, T.Balasubramanian, Dual fluorescence of syringaldazine, Spectrochim Acta, 68A (2007) 894-904, https://doi.org/10.1016/j.saa.2006.12.023 View Article

[16-25]

. Binding constant (K) values were determined from the slopes and intercepts, and the corresponding ΔG values (Table 1) are negative, indicating spontaneous and exothermic inclusion at 303 K.

The distinct spectral changes of 3AS upon addition of CDs at different pH values clearly indicate that the geometry and orientation of the guest molecule inside the cavity differ with pH. At higher CD concentrations, variations in absorption and emission maxima and spectral shapes further confirm the formation of multiple inclusion complexes. Since hydrophobic interactions drive encapsulation, the aromatic ring of 3AS preferentially enters the hydrophobic CD cavity, while the –NH₂ group remains oriented near the rim of the cavity

[16]	N.Rajendiran,T.Mohandoss, G.Venkatesh, Investigation of inclusion complexes of sulfamerazine with α- and β-cyclodextrins: An experimental and theoretical study, Spectrochimica Acta A, 124(2014) 441-450. https://doi.org/10.1016/j.saa.2014.01.018 View Article
[17]	G.Venkatesh, A. Antony Muthu Prabhu, N.Rajendiran, Azonium-Ammonium Tautomerism and Inclusion Complexation of 1-(2,4-diamino phenylazo) naphthalene and 4-Amino azobenzene, J.Fluorescence, 21(2011) 1485-1497. https://doi.org/10.1007/s10895-011-0863-5 View Article
[18]	G.Venkatesh, R. K.Sankara narayanan, A. Antony Muthu Prabhu, N.Rajendiran, Absorption and fluorescence spectral characteristics of norepinephrine, epinephrine, isoprenaline, methyldopa, terbutaline and orciprenaline drugs, Physics and Chemistry of Liquids, 50(2012) 434-452. https://doi.org/10.1080/00319104.2011.589376 View Article
[19]	T.Stalin, R.Anithadevi, N.Rajendiran, Spectral characteristics of ortho, meta and para-dihydroxybenzenes in different solvents, pH and β-CD. Spectrochimica Acta, 61A (2005) 2495-2504. https://doi.org/10.1016/j.saa.2004.12.031 View Article
[20]	T.Stalin, P. Vasantharani, B.Shanthi, A.Sekar, N.Rajendiran, Inclusion complex of 1,2,3-trihydroxybenzene with α- and β-cyclodextrins, Indian J Chemistry, 45A (2006) 1113-1120.
[21]	K.Sivakumar, T.Stalin, N.Rajendiran, Dual fluorescence of diphenyl carbazide and benzanilide: Effect of solvents and pH on electronic spectra, Spectrochimica Acta, 62A (2005) 991-999. https://doi.org/10.1016/j.saa.2005.02.011 View Article
[22]	J.Prema Kumari, A. Antony Muthu Prabhu, G. Venkatesh, V. K. Subramanian, N.Rajendiran, Effect of solvents and pH on β-CD Inclusion complexation of 2,4-dihydroxyazobenzene and 4-hydroxy azobenzene, J.Solution Chemistry, 40(2011) 327-347. https://doi.org/10.1007/s10953-011-9654-7 View Article
[23]	J. Thulasidhasan, N. Rajendiran, Host-guest inclusion complexes of propafenone hydrochloride with α- and β-cyclodextrins: Spectral and molecular modeling study, Spectrochim Acta, 115A (2013) 559-567. https://doi.org/10.1016/j.saa.2013.06.066 View Article
[24]	J.Prema Kumari, A. Antony Muthu Prabhu, G.Venkatesh, V. K.Subramanian, N. Rajendiran, Spectral characteristics of sulfadiazine, sulfisomidine: Effect of solvents, pH and β-CD, Physics and Chemistry of Liquids, 49(2011) 108-132. https://doi.org/10.1080/00319100903563634 View Article
[25]	N.Rajendiran, T.Balasubramanian, Dual fluorescence of syringaldazine, Spectrochim Acta, 68A (2007) 894-904, https://doi.org/10.1016/j.saa.2006.12.023 View Article

[16-25]

3.2. Intramolecular Charge Transfer Emission (ICT)

3AS exhibits dual emission in CD solutions. At pH ~2 and pH ~11, above 4 × 10⁻³ M β-CD, a dual‐band emission characteristic of an intramolecular charge-transfer (ICT) state appears. The ICT band, however, is very weak at pH ~11. These observations suggest that polarity, viscosity, and the size of the CD cavity play a significant role in modulating the ICT behaviour of 3AS.

To verify the origin of the dual emission in the 3AS–β-CD system, the solvent-induced variations in the absorption and emission spectra of 3AS were examined in selected solvents. The spectral maxima of 3AS in cyclohexane, acetonitrile, methanol, and water are as follows: (cyclohexane: λ_abs ≈ 285, 234 nm; λ_flu ≈ 309 nm, acetonitrile: λ_abs ≈ 288, 240 nm; λ_flu ≈ 323 nm, methanol: λ_abs ≈ 286, 237 nm; λ_flu ≈ 327 nm, water: λ_abs ≈ 284, 230 nm; λ_flu ≈ 334 nm).

These trends are comparable to those reported for 3-aminophenol (3AP)

[31]

(cyclohexane: λ_abs ≈ 286, 236 nm; λ_flu ≈ 314 nm; acetonitrile: λ_abs ≈ 288, 239 nm; λ_flu ≈ 324 nm; methanol: λ_abs≈ 283, 232 nm; λ_flu ≈ 320 nm; water: λ_abs ≈ 281, 232 nm; λ_flu ≈ 336 nm). Importantly, 3AS exhibits a single broad emission band in all these solvents. The absence of any longer-wavelength emission demonstrates that ICT, exciplex, or excimer formation does not occur in homogeneous solvents.

In contrast, while 3AS shows only a single emission band in all solvents, it displays dual luminescence in both α-CD and β-CD. The dual emission consists of a shorter-wavelength (SW) band (337–356 nm) and a longer-wavelength (LW) band (435–442 nm). Increasing β-CD concentration causes both bands to undergo red shifts, with the shift being more pronounced for the SW band.

The LW band becomes progressively red-shifted and its intensity increases steadily from lower to higher β-CD concentrations

[32-36]

. Moreover, the LW intensity grows with increasing excitation wavelength (λ_exci 260–300 nm). At pH ~11, the SW emission undergoes a larger red shift (337→356 nm) than the LW band (435→442 nm) (Table 1). These features indicate the formation of an ICT state in 3AS, similar to the behaviour reported for aminobenzoic acids and hydroxy benzaldehydes

[34-38]

. The appearance of the LW band at high CD concentrations clearly confirms the presence of ICT emission in 3AS.

The key question is why 3AS does not exhibit ICT emission in solvents. In free solution, 3AS molecules can rotate freely, which disfavour’s ICT formation. In contrast, the CD cavity restricts molecular rotation. Moreover, 3AS is only partially included in α-CD but becomes deeply embedded in the nonpolar region of the β-CD cavity. Within α-CD, the guest experiences a much less polar environment, suppressing ICT emission and consequently enhancing the normal band. The geometrical constraints of the α-CD cavity also limit the rotational freedom of the amino or methoxy groups, hindering ICT state formation and enhancing the normal fluorescence.

At higher β-CD concentrations, the emission maxima and spectral profiles of 3AS at pH ~7 and pH ~11 become similar, indicating ICT formation under both conditions. This is reasonable because, at pH ~7, the protonated amino group is more polar and can engage in hydrogen bonding with the secondary –OH groups on the CD rim or with bulk water molecules. The large rim of α-CD and β-CD, which contain 12 and 14 secondary hydroxyl groups respectively, provides an environment qualitatively similar to polyhydroxy alcohols

[1-8]

3.3. Excited Singlet State Lifetimes

To examine the CD-induced changes in the fluorescence behaviour of 3AS, the emission decays of the normal and ICT bands were analysed in aqueous α-CD and β-CD solutions (Table 1). For 3AS, biexponential decay was observed in water and α-CD. In β-CD, biexponential decay appeared at pH ~2, whereas triexponential decay was detected at pH ~7 and pH ~11. This decay pattern indicates the presence of two different emitting species whose populations compete with the conformational relaxation times required for ICT formation. The shorter-lived, low-intensity component corresponds to the ICT emission, suggesting that an equilibrium between the locally excited (LE) state and the ICT state is established rapidly in water. In β-CD, however, the LE–ICT equilibrium is altered due to the formation of inclusion complexes. The LE lifetime increases slightly from water to α-CD and β-CD.

Upon addition of α-CD, the ICT emission exhibits a weak triexponential decay without a significant enhancement in lifetime. In contrast, in β-CD the ICT emission decay clearly shows a triexponential profile, indicating the formation of distinct 3AS: α-CD and 3AS: β-CD inclusion complexes. The lifetimes of the guest–host complexes are higher than those of the free guest molecule, and the lifetime increases with increasing CD concentration, consistent with encapsulation of 3AS inside the CD cavity. The lifetime of 3AS follows the order: water < α-CD < β-CD, indicating that the 3AS: β-CD complex is more stable than the 3AS: α-CD complex. These observations confirm that the ICT dynamics of 3AS in α-CD differ markedly from those in β-CD.

3.4. Molecular Modeling

The ground-state geometries of 3AS and the CDs were optimized using the PM3 method, and the resulting structures were used to construct the inclusion complex models (Figure 3). The corresponding thermodynamic parameters for 3AS, α-CD, β-CD, and their complexes are listed in Table 2. In free 3AS, the vertical and horizontal distances between the –NH₂ and –OCH₃ groups are 6.57 Å and 6.01 Å, respectively (Figure 3). These dimensions can be compared with the CD cavity sizes: α-CD has an internal diameter of 4.7–5.3 Å and β-CD has an internal diameter of 6.0–6.5 Å; the external diameters are 8.8 Å (α-CD) and 10.8 Å (β-CD), with a height of ~7.8 Å.

The vertical distance in 3AS is slightly smaller than both CD cavity diameters, while the horizontal distance exceeds the α-CD cavity size. As a result, 3AS cannot be fully inserted into α-CD, whereas β-CD has a sufficiently large cavity to allow deeper penetration. These geometric considerations indicate that 3AS forms different types of inclusion complexes with α-CD and β-CD. The optimized structures further confirm that 3AS is only partially included in both CD cavities.

Significant changes in HOMO and LUMO energies, free energy, enthalpy, entropy, dipole moment, and zero-point vibrational energy between the free 3AS molecule and the 3AS: CD complexes demonstrate successful formation of inclusion complexes. The polarity of the CD cavity changes upon guest encapsulation. The negative values of ΔE, ΔH, and ΔG indicate that the inclusion process is energetically and enthalpically favourable. The small negative ΔS value reflects the slight increase in disorder that accompanies complex formation.

Table 2. Thermodynamic parameters and HOMO-LUMO energy calculations for 3AS and its inclusion complex by PM3 method.

Properties	3AS	α-CD	β-CD	3AS: α-CD	3AS: β-CD
E_HOMO (eV)	-8.47	-10.37	-10.35	-8.18	-8.29
E_LUMO(eV)	0.54	1.26	1..23	0.69	0.76
E_HOMO – E_LUMO(eV)	-9.01	-11.63	-11.58	-8.87	-9.05
Dipole moment (D)	1.19	11.34	12.29	11.63	11.84
E*	-21.36	-1247.62	-1457.63	-1253.99	-1467.84
E*				-14.99	-1254.30
G*	65.05	-676.37	-789.52	-586.17	-695.92
ΔG*				-25.15	-28.55
H*	92.11	-570.84	-667.55	-524.19	-628.94
ΔH				-45.41	-53.5
S**	0.090	0.353	0.409	0.452	0.461
ΔS**				0.009	0.038
ZPE*	68.39	635.09	740.56	708.32	811.36
Mullikan charge	0.00	0.00	0.00	0.00	0.00

* kcal/mol; **kcal/mol-Kelvin; ZPE = Zero point vibration energy

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Figure 3. PM3 optimized structures of (a, b) 3AS (c, d) HOMO, LUMO of 3AS.

4. Nanomaterial Studies

4.1. Scanning Electron Microscopy

The powdered forms of Ag nanoparticles, 3AS, and the nano Ag: 3AS: α-CD and nano Ag: 3AS: β-CD inclusion complex nanomaterials were examined using SEM (Figure 4). The micrographs clearly reveal the morphological differences between pure Ag nanoparticles, free 3AS, and their corresponding silver nanoparticle–inclusion complex systems. SEM-EDX analysis confirmed the presence of 34.2% carbon, 44.2% oxygen, and 21.6% silver in the nanomaterials. The distinct morphologies observed for nano Ag, 3AS, and their inclusion complexes support the successful formation of Ag–3AS–CD nanomaterials. The modification in particle shape and surface features further serves as evidence for the generation of new Ag: 3AS: CD inclusion complex nanostructures

[35-39]

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Figure 4. SEM photographs of (a) 3AS, (b) nano Ag: 3AS: α-CD, (b) nano Ag: 3AS: β-CD.

4.2. Differential Scanning Colorimeter

The DSC profiles of α-CD, β-CD, 3AS, and their respective inclusion complexes were analyzed

[40-45]

. The thermogram of α-CD shows three endothermic peaks at 79.2°C, 109.1°C, and 137.5°C, while β-CD exhibits a broad endothermic transition at 128.6°C, all corresponding to the release of crystal water. For 3AS, a sharp peak is observed at 251°C (boiling point), and its melting point is 0°C. A broad endothermic effect was recorded for α-CD, β-CD, and their inclusion complexes due to water loss. Importantly, the DSC thermograms of the inclusion complexes no longer display the characteristic peaks of pure 3AS or CDs; instead, new peaks appear at 255°C and 276°C for 3AS: α-CD and 3AS: β-CD, respectively, confirming the formation of new inclusion complexes.

4.3. Infrared Spectral Studies

FTIR spectroscopy was used to investigate host–guest interactions

[40-44]

. For free 3AS, the –NH stretching frequencies appear at 3449 and 3369 cm^-1, while the –C–H stretching band occurs at 2637 cm^-1. The aromatic C–H and C–O stretching vibrations are observed at 3026 and 1292 cm^-1, respectively. The O–CH₃ stretching and CH₃ deformation bands appear at 2837 and 1355 cm^-1. Additionally, the NH₂ deformation and aromatic ring deformation bands are noted at 1625 and 577 cm^-1.

In the Ag: 3AS: CD nanomaterials, the –NH stretching band shifts to 3308 cm^-1, while the aromatic C–H and C=C stretching frequencies appear at 2890 cm^-1 and 1720 cm^-1, respectively. The C–O stretching band originally at 1355 cm^-1 shifts to 1333 cm^-1 in the nanomaterials. A characteristic Ag nanoparticle band is detected at 575 cm^-1. The disappearance of several characteristic frequencies of 3AS and the significant reduction in intensities in the Ag: 3AS: CD spectra indicate strong interactions between 3AS, silver nanoparticles, and cyclodextrin, confirming the formation of the Ag–3AS–CD nanocomposite.

4.4. X RD Spectral Studies

The crystallinity of all nanoparticles was examined using XRD analysis

[44-48]

. Pure Ag nanoparticles exhibited strong diffraction peaks at 38.11°, 44.30°, 64.45°, and 77.40°, corresponding to the characteristic reflections of the face-centered cubic (fcc) structure of metallic silver. The XRD pattern of α-CD shows crystalline reflections at approximately 11.94°, 14.11°, and 21.77°, whereas β-CD exhibits peaks at 11.49° and 17.58°; however, the intensity and presence of these peaks may vary depending on sample conditions and preparation methods. Because 3AS is a liquid at room temperature (melting point 6.2°C), it does not produce a typical powder XRD pattern with sharp crystalline peaks.

The XRD pattern of Ag/3AS: β-CD nanomaterials displays distinct diffraction peaks at 11.11°, 18.27°, 29.26°, 35.73°, 46.61°, 55.86°, 66.04°, and 74.75°. The observed variations in peak intensities and positions compared to the pure components indicate the formation of a new nanomaterial, supporting successful inclusion and interaction between Ag nanoparticles, 3AS, and β-CD.

4.5. ¹H NMR Spectral Studies

To further investigate the structural features of 3AS and its cyclodextrin complexes, ¹H NMR spectra were recorded. The proton resonances of CDs are well documented and include six types of protons. Among these, the H-3 and H-5 protons lie inside the CD cavity; therefore, their chemical shifts are strongly influenced upon guest inclusion. In contrast, the H-1, H-2, and H-4 protons, located on the outer surface, typically show only minor changes. Guest molecules generally exhibit noticeable chemical shift variations when included in the CD cavity.

¹H NMR spectra of 3AS and its inclusion complexes were recorded at 25°C in DMSO-d₆ (Table 3). In both α-CD and β-CD complexes, the proton signals of 3AS shift upfield, indicating shielding effects due to encapsulation within the hydrophobic cyclodextrin cavity. These observations confirm that all major protons of 3AS interact with the internal cavity protons of CDs, supporting the formation of host–guest inclusion complexes.

Table 3. ¹H-NMR chemical shift values for the 3AS and Ag: 3AS: α-CD nanomaterials.

Protons	3AS (δ)	Ag: 3AS: α-CD (Δδ)	Ag: 3AS: β-CD (Δδ)
H_a- meta to NH₂, OCH₃	7.03	7.38w	7.4w
H_b- para to NH₂	6.30	7.18w	7.2w
H_c- para to OCH₃	6.24	6.78w	6.80w
H_d- in between to NH₂, OCH₃	6.21	4.81	4.84
H_e -OCH₃	3.72	2.46	2.49
H_f - NH₂	3.59	2.06	2.08

5. Conclusion

The spectral variations observed for 3AS in the presence of CDs at pH ~2, pH ~7, and pH ~11 indicate that the structural geometry of the resulting inclusion complexes varies with pH. While 3AS exhibits a single emission maximum in aqueous solutions, dual emission is observed in CD environments. The restricted geometry of the α-CD cavity limits the rotational freedom of the amino or methoxy group of 3AS, hindering ICT-state formation and enhancing normal emission. The fluorescence decay behavior of 3AS reveals the presence of two emitting species, whose competition influences the conformational relaxation dynamics associated with ICT formation. 3AS is only partially included within the α-CD cavity but is more deeply encapsulated in the hydrophobic interior of β-CD. SEM imaging and EDX analysis confirm that the Ag: 3AS: CD nanomaterials contain 34.2% carbon, 44.2% oxygen, and 21.6% silver. FTIR spectra show the disappearance of several characteristic 3AS peaks, along with significant decreases in band intensities for the Ag: 3AS: CD complexes, confirming strong interactions between 3AS and Ag nanoparticles. In ¹H NMR spectra, the chemical shifts of 3AS protons move both upfield and downfield, and signal intensities decrease markedly, supporting the formation of Ag-incorporated CD inclusion nanomaterials.

Abbreviations

FTIR	Fourier Transform Infrared Spectroscopy
DTA	Differential Thermal Analysis
XRD	X-ray Diffraction
SEM	Scanning Electron Microscopy
HOMO	Highest Occupied Molecular Orbital
LUMO	Lowest Unoccupied Molecular Orbital
3AS	3-Anisidine
Ag NPs	Silver Nanoparticles
α-CD	Alpha Cyclodextrin
β-CD	Beta Cyclodextrin
PM3	Parametric Method 3
ΔE	Iinternal Energy Change
ΔH	Enthalpy Change
ΔG	Free Energy Change
ΔS	Entropy Change

Author Contributions

Narayanasamy Rajendiran: Supervision, Resources, Methodology, Software, Writing – original draft, Writing – review & editing

Ayyadurai Mani: Formal Analysis, Investigation

Palanichamy Ramasamy: Data curation, calculation.

Sengamalai Senthilmurugan: Validation

Conflicts of Interest

The authors declare no conflict of interest.

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Rajendiran, N., Mani, A., Ramasamy, P., Senthilmurugan, S. (2026). Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH. American Journal of Nanosciences, 10(2), 41-51. https://doi.org/10.11648/j.ajn.20261002.11

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Rajendiran, N.; Mani, A.; Ramasamy, P.; Senthilmurugan, S. Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH. Am. J. Nanosci. 2026, 10(2), 41-51. doi: 10.11648/j.ajn.20261002.11

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Rajendiran N, Mani A, Ramasamy P, Senthilmurugan S. Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH. Am J Nanosci. 2026;10(2):41-51. doi: 10.11648/j.ajn.20261002.11

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@article{10.11648/j.ajn.20261002.11,
  author = {Narayanasamy Rajendiran and Ayyadurai Mani and Palanichamy Ramasamy and Sengamalai Senthilmurugan},
  title = {Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH},
  journal = {American Journal of Nanosciences},
  volume = {10},
  number = {2},
  pages = {41-51},
  doi = {10.11648/j.ajn.20261002.11},
  url = {https://doi.org/10.11648/j.ajn.20261002.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajn.20261002.11},
  abstract = {The spectral properties of the silver–3-anisidine–cyclodextrin (Ag: 3AS: CD) inclusion complex nanomaterials in solution were investigated using UV–visible, steady-state fluorescence, time-resolved fluorescence, SEM, DSC, FTIR, XRD, 1H NMR, and molecular modeling methods. The distinct spectral changes observed for 3AS upon the addition of CDs at different pH values indicate that the geometries of the resulting inclusion complexes vary with pH. While 3AS exhibits a single emission maximum in solvents and in α-CD, a dual emission is observed in β-CD. The lifetimes of the inclusion complexes were longer than that of the free 3AS molecule. The relatively narrow cavity of α-CD likely restricts the free rotation of the amino or methoxy groups of 3AS, inhibiting ICT-state formation and thereby enhancing the normal emission. The calculated HOMO–LUMO energy gap, total energy, free energy, enthalpy, entropy, dipole moment, and zero-point vibrational energy of the CD: 3AS complex differed significantly from those of the isolated 3AS, α-CD and β-CD molecules, and both the vertical and horizontal bond lengths between the amino and methoxy groups are smaller than the β-CD cavity size confirming the formation of an inclusion complex. SEM images and EDX analysis confirm the presence of silver in the Ag: 3AS: β-CD nanomaterials. In the FTIR spectra, most characteristic peaks diminish or disappear, accompanied by a marked decrease in intensity for the Ag: 3AS: CD nanocomplexes, suggesting strong interactions between 3AS and nano silver. The 1H NMR chemical shifts of 3AS protons move both upfield and downfield indicating restricted mobility and strong host–guest interactions within the nano Ag–CD matrix.},
 year = {2026}
}

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TY  - JOUR
T1  - Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH
AU  - Narayanasamy Rajendiran
AU  - Ayyadurai Mani
AU  - Palanichamy Ramasamy
AU  - Sengamalai Senthilmurugan
Y1  - 2026/04/13
PY  - 2026
N1  - https://doi.org/10.11648/j.ajn.20261002.11
DO  - 10.11648/j.ajn.20261002.11
T2  - American Journal of Nanosciences
JF  - American Journal of Nanosciences
JO  - American Journal of Nanosciences
SP  - 41
EP  - 51
PB  - Science Publishing Group
SN  - 2575-4858
UR  - https://doi.org/10.11648/j.ajn.20261002.11
AB  - The spectral properties of the silver–3-anisidine–cyclodextrin (Ag: 3AS: CD) inclusion complex nanomaterials in solution were investigated using UV–visible, steady-state fluorescence, time-resolved fluorescence, SEM, DSC, FTIR, XRD, 1H NMR, and molecular modeling methods. The distinct spectral changes observed for 3AS upon the addition of CDs at different pH values indicate that the geometries of the resulting inclusion complexes vary with pH. While 3AS exhibits a single emission maximum in solvents and in α-CD, a dual emission is observed in β-CD. The lifetimes of the inclusion complexes were longer than that of the free 3AS molecule. The relatively narrow cavity of α-CD likely restricts the free rotation of the amino or methoxy groups of 3AS, inhibiting ICT-state formation and thereby enhancing the normal emission. The calculated HOMO–LUMO energy gap, total energy, free energy, enthalpy, entropy, dipole moment, and zero-point vibrational energy of the CD: 3AS complex differed significantly from those of the isolated 3AS, α-CD and β-CD molecules, and both the vertical and horizontal bond lengths between the amino and methoxy groups are smaller than the β-CD cavity size confirming the formation of an inclusion complex. SEM images and EDX analysis confirm the presence of silver in the Ag: 3AS: β-CD nanomaterials. In the FTIR spectra, most characteristic peaks diminish or disappear, accompanied by a marked decrease in intensity for the Ag: 3AS: CD nanocomplexes, suggesting strong interactions between 3AS and nano silver. The 1H NMR chemical shifts of 3AS protons move both upfield and downfield indicating restricted mobility and strong host–guest interactions within the nano Ag–CD matrix.
VL  - 10
IS  - 2
ER  -

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Narayanasamy Rajendiran

Department of Chemistry, Annamalai University, Annamalai Nagar, India

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http://orcid.org/0000-0002-5860-6609
Ayyadurai Mani

Department of Chemistry, Annamalai University, Annamalai Nagar, India

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http://orcid.org/0009-0007-9024-7179
Palanichamy Ramasamy

Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India

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http://orcid.org/0000-0003-0393-0417
Sengamalai Senthilmurugan

Department of Zoology, Annamalai University, Annamalai Nagar, India

http://orcid.org/0000-0003-0204-4245

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Rajendiran, N., Mani, A., Ramasamy, P., Senthilmurugan, S. (2026). Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH. American Journal of Nanosciences, 10(2), 41-51. https://doi.org/10.11648/j.ajn.20261002.11

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Rajendiran, N.; Mani, A.; Ramasamy, P.; Senthilmurugan, S. Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH. Am. J. Nanosci. 2026, 10(2), 41-51. doi: 10.11648/j.ajn.20261002.11

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AMA Style

Rajendiran N, Mani A, Ramasamy P, Senthilmurugan S. Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH. Am J Nanosci. 2026;10(2):41-51. doi: 10.11648/j.ajn.20261002.11

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@article{10.11648/j.ajn.20261002.11,
  author = {Narayanasamy Rajendiran and Ayyadurai Mani and Palanichamy Ramasamy and Sengamalai Senthilmurugan},
  title = {Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH},
  journal = {American Journal of Nanosciences},
  volume = {10},
  number = {2},
  pages = {41-51},
  doi = {10.11648/j.ajn.20261002.11},
  url = {https://doi.org/10.11648/j.ajn.20261002.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajn.20261002.11},
  abstract = {The spectral properties of the silver–3-anisidine–cyclodextrin (Ag: 3AS: CD) inclusion complex nanomaterials in solution were investigated using UV–visible, steady-state fluorescence, time-resolved fluorescence, SEM, DSC, FTIR, XRD, 1H NMR, and molecular modeling methods. The distinct spectral changes observed for 3AS upon the addition of CDs at different pH values indicate that the geometries of the resulting inclusion complexes vary with pH. While 3AS exhibits a single emission maximum in solvents and in α-CD, a dual emission is observed in β-CD. The lifetimes of the inclusion complexes were longer than that of the free 3AS molecule. The relatively narrow cavity of α-CD likely restricts the free rotation of the amino or methoxy groups of 3AS, inhibiting ICT-state formation and thereby enhancing the normal emission. The calculated HOMO–LUMO energy gap, total energy, free energy, enthalpy, entropy, dipole moment, and zero-point vibrational energy of the CD: 3AS complex differed significantly from those of the isolated 3AS, α-CD and β-CD molecules, and both the vertical and horizontal bond lengths between the amino and methoxy groups are smaller than the β-CD cavity size confirming the formation of an inclusion complex. SEM images and EDX analysis confirm the presence of silver in the Ag: 3AS: β-CD nanomaterials. In the FTIR spectra, most characteristic peaks diminish or disappear, accompanied by a marked decrease in intensity for the Ag: 3AS: CD nanocomplexes, suggesting strong interactions between 3AS and nano silver. The 1H NMR chemical shifts of 3AS protons move both upfield and downfield indicating restricted mobility and strong host–guest interactions within the nano Ag–CD matrix.},
 year = {2026}
}

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TY  - JOUR
T1  - Preparation of 3-Anisidine–Cyclodextrin Doped Silver Nanomaterials and Investigation of 3AS–CD Inclusion Complex at Different pH
AU  - Narayanasamy Rajendiran
AU  - Ayyadurai Mani
AU  - Palanichamy Ramasamy
AU  - Sengamalai Senthilmurugan
Y1  - 2026/04/13
PY  - 2026
N1  - https://doi.org/10.11648/j.ajn.20261002.11
DO  - 10.11648/j.ajn.20261002.11
T2  - American Journal of Nanosciences
JF  - American Journal of Nanosciences
JO  - American Journal of Nanosciences
SP  - 41
EP  - 51
PB  - Science Publishing Group
SN  - 2575-4858
UR  - https://doi.org/10.11648/j.ajn.20261002.11
AB  - The spectral properties of the silver–3-anisidine–cyclodextrin (Ag: 3AS: CD) inclusion complex nanomaterials in solution were investigated using UV–visible, steady-state fluorescence, time-resolved fluorescence, SEM, DSC, FTIR, XRD, 1H NMR, and molecular modeling methods. The distinct spectral changes observed for 3AS upon the addition of CDs at different pH values indicate that the geometries of the resulting inclusion complexes vary with pH. While 3AS exhibits a single emission maximum in solvents and in α-CD, a dual emission is observed in β-CD. The lifetimes of the inclusion complexes were longer than that of the free 3AS molecule. The relatively narrow cavity of α-CD likely restricts the free rotation of the amino or methoxy groups of 3AS, inhibiting ICT-state formation and thereby enhancing the normal emission. The calculated HOMO–LUMO energy gap, total energy, free energy, enthalpy, entropy, dipole moment, and zero-point vibrational energy of the CD: 3AS complex differed significantly from those of the isolated 3AS, α-CD and β-CD molecules, and both the vertical and horizontal bond lengths between the amino and methoxy groups are smaller than the β-CD cavity size confirming the formation of an inclusion complex. SEM images and EDX analysis confirm the presence of silver in the Ag: 3AS: β-CD nanomaterials. In the FTIR spectra, most characteristic peaks diminish or disappear, accompanied by a marked decrease in intensity for the Ag: 3AS: CD nanocomplexes, suggesting strong interactions between 3AS and nano silver. The 1H NMR chemical shifts of 3AS protons move both upfield and downfield indicating restricted mobility and strong host–guest interactions within the nano Ag–CD matrix.
VL  - 10
IS  - 2
ER  -

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