Thambusamy Stalin

Spectral and electrochemical study of host-guest inclusion complex between 2,4-dinitrophenol and β-cyclodextrin.

The formation of host-guest inclusion complex of 2,4-dinitrophenol (2,4-DNP) with nano-hydrophobic cavity of β-cyclodextrin (β-CD) in solution phase was studied by UV-visible spectrophotometer and electrochemical method (cyclic voltammetry, CV). The prototropic behaviors of 2,4-DNP with and without β-CD and the ground state acidity constant (pK(a)) of host-guest inclusion complex (2,4-DNP-β-CD) were studied. The binding constant of inclusion complex at 303K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (ΔG) was also calculated. The solid inclusion complex formation between β-CD and 2,4-DNP was confirmed by (1)H NMR, FT-IR, XRD and SEM analysis. A schematic representation of this inclusion process is proposed by molecular docking studies using PatchDock server.

Study of inclusion complex of β-cyclodextrin and diphenylamine: Photophysical and electrochemical behaviors

The photophysical, electrochemical and photoprototropic behaviors of diphenylamine (DPA) in aqueous β-cyclodextrin (β-CD) solution have been investigated using absorption spectroscopy and cyclic voltammetric techniques. Absorption of the neutral and cationic form of DPA is enhanced due to the formation of a 1:1 complex with β-CD. The formation of this complex has been confirmed by Benesi-Hildebrand plot and docking studies by RasMol tool methods. The solid complex of β-CD with DPA is investigated by FT-IR, XRD and AFM methods. The thermodynamic parameters (ΔG, ΔH and ΔS) of inclusion process are also determined. The pK(a) values of neutral-monocation equilibria have been determined with absorption (conjugate acid-base) titrations. A mechanism is proposed to explain the inclusion process.

Improvement on dissolution rate of inclusion complex of Rifabutin drug with β-cyclodextrin

The effect of β-cyclodextrin (β-CD) on the improvement of solubility and antimicrobial activity of poorly water soluble drug Rifabutin (RFB) was studied. The solid inclusion complex is prepared under different methods and it is characterized by FT-IR, XRD, DSC and SEM methods. Solubility type, stability constant, stoichiometric ratio were investigated from phase solubility diagram of inclusion complex (RFB with β-CD). The dissolution profiles of the inclusion complexes were carried out and obvious increase in dissolution rate was observed when compared with pure RFB drug. Inclusion complexation process was further confirmed by molecular docking studies using PatchDock server. The in vitro antimicrobial and antibiofilm activity of RFB sensible microorganisms was significantly increased by on inclusion complexation process. This trend of inclusion complexation of poorly water soluble drugs is highly recognized as a successful and useful approach for the application in pharmaceutical field.

Preparation and characterizations of solid/aqueous phases inclusion complex of 2,4-dinitroaniline with β-cyclodextrin

The formation of host-guest inclusion complex of 2,4-dinitroaniline (2,4-DNA) with nano-hydrophobic cavity of β-cyclodextrin (β-CD) in solution phase were studied by UV-visible spectrophotometer and electrochemical method (Cyclic Voltammetry, CV). The prototropic behaviors of 2,4-DNA with and without β-CD was studied by spectrophotometrically. The binding constant of the inclusion complex at 303K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (ΔG) were also calculated. The inclusion complex formation between β-CD and 2,4-DNA was confirmed by (1)H NMR, 2D ROESY NMR, FT-IR, XRD and SEM analysis. The 2,4-DNA:β-CD inclusion complex was obtained by molecular docking studies and it was good correlation with the results obtained through experimental methods.

N-phenyl-1-naphthylamine/β-cyclodextrin inclusion complex as a new fluorescent probe for rapid and visual detection of Pd2+

Inclusion complex between N-phenyl-1-naphthylamine (NPN) and β-cyclodextrin (β-CD) was studied by FT-IR, (1)H and 2D NMR, XRD, FT-Raman, SEM and DSC techniques. The formation of 1:1 stoichiometric inclusion complex of NPN with β-CD was proposed based on the Nuclear magnetic resonance spectroscopy and Molecular docking study. The molecular encapsulation of host-guest inclusion complex based on simple chemosensor has high selectivity and sensitivity for the determination of Pd(2+) ion. Host-guest inclusion complex as a spectroscopic probe is used for the detection of transition metal cation Pd(2+). Coordination of this Pd(2+) with (NPN/β-CD) inclusion complex exhibited a noticeable color change in the solution state it used for naked-eye detection.

2,6-Dinitroaniline and β-cyclodextrin inclusion complex properties studied by different analytical methods

The formation of supramolecular host-guest inclusion complex of 2,6-Dinitroaniline (2,6-DNA) with nano-hydrophobic cavity of β-cyclodextrin (β-CD) in solution phase were studied by UV-visible spectrophotometer and electrochemical method (cyclic voltammetry, CV). The prototropic behaviors of 2,6-DNA with and without β-CD and the ground state acidity constant (pKa) of host-guest inclusion complex (2,6-DNA-β-CD) was studied by Spectrophotometrically. The binding constant of inclusion complex at 303 K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (ΔG) were also calculated. The solid inclusion complex formation between β-CD and 2,6-DNA was confirmed by (1)H NMR, FT-IR, XRD and SEM analysis. The β-CD:2,6-DNA inclusion complex obtained by molecular docking studies is in good correlation with the results obtained through experimental methods.

A highly selective dual mode detection of Fe3+ ion sensing based on 1,5-dihydroxyanthraquinone in the presence of β-cyclodextrin.

1,5-Dihydroxyanthraquinone (1,5-DHAQ) and in the presence of β-cyclodextrin (β-CD) has been used to find Fe(3+) ion in aqueous solution by UV-visible and fluorescence spectroscopy. The chromo-fluorogenic probe undergoes absorption and emission intensity enhancement upon binding to Fe(3+) ion in pH~7 aqueous solutions. The enhancement of the chemosensor probe is attributed to a 1:1 inclusion complex formation between β-CD and 1,5-DHAQ, which has been utilized as the basis for selective detection of Fe(3+) ion. The chemosensors can be applied to the selectivity and sensitivity analysis which showed that the remarkable sensing limit of detection (LOD) was 7.3∗10(-7)M (β-CD/1,5-DHAQ:Fe(3+)). The proposed chemosensors based on 1,5-DHAQ and in the presence of β-CD has a good selectivity, sensitivity and potential application to the determination of Fe(3+) ion in environmental and biological systems.

Fluorometric sensing of Pb2+ and CrO42− ions through host–guest inclusion for human lung cancer live cell imaging

The formation of an inclusion complex between 1,5-dihydroxyanthraquinone (1,5-DHAQ; 1) and β-cyclodextrin (β-CD) in aqueous media has been studied by UV-visible and fluorescence spectroscopy. A solid inclusion complex (β-CD:1,5-DHAQ; 2) has been prepared and characterized by FT-IR, XRD, DSC and SEM analyses. The chemosensor probes 1 and 2 showed selective recognition and sensing ability towards the Pb2+ and CrO42− ions. The association constants (Ka) of 2·Pb2+ and Stern–Volmer quenching constant (Ksv) of 2·CrO42− were obtained to be 1.6 × 103 M−1 and 1.9 × 106 M−1 in water, and the corresponding detection limits were calculated to be 9.0 × 10−8 and 3.9 × 10−8 M according to fluorescence titration analysis. Theoretical studies on molecular docking and density functional theory (DFT) calculations have been performed to prove the binding of Pb2+ and CrO42− ions with chemosensor probes 1 and 2. Furthermore, bio-imaging indicated that these probes 1 and 2 have good cell permeability and are suitable for monitoring intracellular uptake of Pb2+ and CrO42− ions in living cells (human lung cancer A549) by confocal microscopy.

Study of inclusion complex between 2,6-dinitrobenzoic acid and β-cyclodextrin by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD, SEM and photophysical methods.

The formation of host-guest inclusion complex of 2,6-dinitrobenzoic acid (2,6-DNB) with nano-hydrophobic cavity of β-cyclodextrin (β-CD) in solution phase has been studied by UV-visible spectroscopy and electrochemical analysis (cyclic voltammetry, CV). The effect of acid-base concentrations of 2,6-DNB has been studied in presence and absence of β-CD to determination for the ground state acidity constant (pKa). The binding constant of inclusion complex at 303 K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (ΔG) was also calculated. The solid inclusion complex formation between β-CD and 2,6-DNB was confirmed by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD and SEM analysis. A schematic representation of this inclusion process was proposed by molecular docking studies using patch dock server.

A new fluorescent PET sensor probe for Co2+ ion detection: computational, logic device and living cell imaging applications

The hydrophobic nature of β-cyclodextrin (β-CD) increases the solubility and stability of 1,2-dihydroxyanthraquinone (1,2-DHAQ; 1) and hence permits the coordination of 1 with cations in aqueous solution; this has been investigated by means of UV-visible and fluorescence spectroscopy. β-CD:1,2-DHAQ (2) demonstrates colorimetric recognition behavior toward Co2+ ion by changing the color of the solution, which can be easily detected with the naked eye. The chemosensor 2 showed good fluorescence behavior upon interaction with various cations; it displayed strong fluorescence quenching (Co2+; ∼80% switch-off) as a fluorescent chemosensor based on photoinduced electron transfer (PET). Moreover, when the 2·Co2+ complex was tested with various anions, only nitrate (NO3−) enabled cobalt binding (as CoNO3) and led to fluorescence enhancement (∼82%; switch-on). The detection limits of sensor 2 with Co2+ and NO3− were found to be 22.7 nM and 2.4 nM. Theoretical molecular docking studies and density functional theory (DFT) calculations were performed to study the binding of Co2+ and NO3− ions with 2. The changes in the fluorescence of 2 upon addition of Co2+ followed by NO3− can be utilised as an XNOR logic gate. Furthermore, 2 has potential for use in bio-imaging as a fluorescent probe to detect Co2+ ion, followed by sequential detection of NO3− ion by 2·Co2+, in living cells (human cervical cancer HeLa cell line) using confocal laser scanning microscopy.