Somchai Keawwangchai | มหาสารคาม - Academia.edu (original) (raw)

Papers by Somchai Keawwangchai

Research paper thumbnail of Spray coating thin polymeric sensor films for Au 3+

Journal of Applied Polymer Science

Research paper thumbnail of Novel selective and sensitive optical chemosensor based on phenylfluorone derivative for detection of Ge(IV) ion in aqueous solution

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2018

A water soluble chemosensor for Ge ion based on fluorone derivative containing 3,4-bis(2-(diethyl... more A water soluble chemosensor for Ge ion based on fluorone derivative containing 3,4-bis(2-(diethylamino)-2-oxoethoxy)phenyl (R8) has been synthesized. The binding abilities between R8 and 10 equiv. of Na, K, Ca, Fe, Cu, Cd, Hg, Pb, Al, Cr, Fe and Ge ions in 1% v/v EtOH-water (tris-buffer pH 7.0) were studied using UV-vis and fluorescence spectrophotometry. When observed by naked-eyes, the color of R8 changed from yellow-orange to pink and the fluorescent color changed from green to non-fluorescence when complexed with Ge ion. The spectral analysis showed that UV-vis absorption and fluorescence emission intensity of R8 decreased dramatically when Ge ion was added comparing with other ions. To explain this behavior, the quantum calculation was performed using the hybrid density functional at B3LYP /LanL2DZ level of theory. The calculated orbital energies indicated that the decreasing of UV-vis absorption and the quenching of fluorescence were due to the complexation induced metal to li...

Research paper thumbnail of Synthesis of electrochemical and optical anion sensors containing organic dyes

Thesis (Ph.D.)--Chulalongkorn University, 2006 Six chromo-and fluorogenic anion sensors have been... more Thesis (Ph.D.)--Chulalongkorn University, 2006 Six chromo-and fluorogenic anion sensors have been synthesized by coupling the appropriate dithioisocyanate of anthracene derivatives with hexylamine in dichloromethane. The anthracene moieties acted as signaling units and thiourea moieties as binding sites. Anions binding properties of synthetic sensors have been studied by [superscript 1]H-NMR titration (10 mM in DMSO-d[subscript 6] and the 1:1 complexations were confirmed by Job's plots. Compounds L1 and L4 formed the most stable complexes with pimelate. Compounds L3 and L5 formed the most stable complexes with glutarate. Compound L2 formed the most stable complexes with succinate. Binding constants were, therefore, found to be strongly dependent on the chain length of dicarboxylate anions and the distance between thiourea groups. UV-vis titrations of all compounds (0.02 mM in DMSO) showed decreasing of maxima absorption intensity when successive addition of dicarboxylate anions....

Research paper thumbnail of Fluoride Recognition of Amide-and Pyrrole-Based Receptors: A Theoretical Study

The novel amide-based receptors, N-(anthracen-1-yl)-1H-pyrrole-2-carboxamide (1) and N-(8-(1H-pyr... more The novel amide-based receptors, N-(anthracen-1-yl)-1H-pyrrole-2-carboxamide (1) and N-(8-(1H-pyrrole-2-carboxamido) anthracen-1-yl)-1H-pyrrole-2-carboxamide (2) have been designed and investigated for their halide ion recognition using the density functional theory calculations in gas and solvent phases. Electronic and thermodynamic properties of halide ion binding complexes of receptors were investigated. Intermolecular interactions in all the studied complexes occurring via hydrogen bonding are found. The designed receptors 1 and 2 are found to be excellent selectivity for fluoride ion in both gas and solvent phases.

Research paper thumbnail of A density functional investigation of 1,3-bis(4-nitrophenyl)urea as anion receptor

The B3LYP/6-311+G(d,p) optimized structures of 1,3-bis(4-nitrophenyl)urea receptor (1) and its co... more The B3LYP/6-311+G(d,p) optimized structures of 1,3-bis(4-nitrophenyl)urea receptor (1) and its complexes with halide ions F À , Cl À , Br À , oxygen-containing anions NO À 2 , NO À 3 , HCO À 3 , HSO À 4 , H 2 PO À 4 , CH 3 COO À and C 6 H 5 COO À ions were obtained. Binding energies and thermodynamic properties of binding between the receptor 1 and these anions were determined. Binding energies of receptor 1 are in decreasing orders: CH 3 COO À > HCO 3 À $ C 6 H 5 COO À > NO À 2 > H 2 PO À 4 > NO À 3 > HSO À 4 for oxygen-containing anions and F À > Cl À > Br À for halide ions. It was found that the binding energies depend on their hydrogen-bond distances of their binding atoms. It was also found that the complexes of receptor 1 and the studied anions are formed via two-point hydrogen-bonding interactions.

Research paper thumbnail of A theoretical investigation on structures of tripodal thiourea derivatives and their anion recognition

Structural Chemistry, 2011

... authorized users. W. Rakrai Á N. Morakot Á B. Wanno Center of Excellence for Innovation in Ch... more ... authorized users. W. Rakrai Á N. Morakot Á B. Wanno Center of Excellence for Innovation in Chemistry and Department of Chemistry, Faculty of Science, Mahasarakham University, Mahasarakham 44150, Thailand S. Keawwangchai ...

Research paper thumbnail of Quantum chemical investigation on structures of pyrrolic amides functionalized (5,5) single-walled carbon nanotube and their binding with halide ions

Structural Chemistry, 2012

Abstract The structures of mono-and di-podal pyrrolic amides functionalized (5, 5) single-walled ... more Abstract The structures of mono-and di-podal pyrrolic amides functionalized (5, 5) single-walled carbon nanotubes (SWCNTs) and their complexes with fluoride, chloride, and bromide ions were obtained using the two-layered ONIOM (MO: MO) and density ...

Research paper thumbnail of Design and synthesis of thiourea based receptor containing naphthalene as oxalate selective sensor

Journal of Molecular Modeling, 2010

The thiourea based receptor containing naphthalene groups (1), has been successfully designed and... more The thiourea based receptor containing naphthalene groups (1), has been successfully designed and synthesized for application as an oxalate receptor. A density functional theory at B3LYP/6-31G(d,p) level of theory has been applied to predict the binding ability between 1 and selected anions, i.e., oxalate, malonate, succinate, glutarate, dihydrogen phosphate, and hydrogen sulphate. Calculation results point out that receptor 1 shows the strongest interaction to oxalate ion with the binding free energy of 172.48 kcal mol −1. The recognition ability of 1 to the selected anions has been also investigated by means of the absorption and emission techniques. Experimental results are in excellent agreement with the calculation data in which receptor 1 shows highly selective for oxalate ion over the other anions with logβ of 3.82 (0.02) M −1 by means of the size of binding cavity.

Research paper thumbnail of Gas adsorption on the Zn–, Pd– and Os–doped armchair (5,5) single–walled carbon nanotubes

Journal of Molecular Modeling, 2012

The adsorption of NO 2 , NH 3 , H 2 O, CO 2 and H 2 gases on the undoped, Zn-, Pd-and Os-doped ar... more The adsorption of NO 2 , NH 3 , H 2 O, CO 2 and H 2 gases on the undoped, Zn-, Pd-and Os-doped armchair (5,5) single-walled carbon nanotubes (SWCNTs) were studied using density functional method. The adsorptions of these five gases on the Zn-, Pd-and Os-doped SWCNTs are obviously stronger than on the undoped SWCNT and their adsorption abilities are in the same order: NO 2 > NH 3 > H 2 O > CO 2 > H 2. Adsorption energies for all the studied gases on the undoped, Zn-, Pd-and Os-doped SWCNTs computed at the B3LYP/LanL2DZ level are reported.

Research paper thumbnail of Density functional investigation of hydrogen gas adsorption on Fe−doped pristine and Stone−Wales defected single−walled carbon nanotubes

Journal of Molecular Modeling, 2012

The adsorptions of hydrogen molecule of the Fe - doped pristine and Stone - Wales defected armcha... more The adsorptions of hydrogen molecule of the Fe - doped pristine and Stone - Wales defected armchair (5,5) single - walled carbon nanotubes (SWCNTs) compared with the pristine SWCNT were investigated by using the density functional theory at the B3LYP/LanL2DZ level. The doping of Fe atom into SWCNTs occurring via an exothermic process was found. The adsorptions of hydrogen molecule on the Fe - doped structures of either perfect or SW defected SWCNTs are stronger than on their corresponding undoped structures. The structural and electronic properties of the pristine and SW defected SWCNTs, their Fe - doped structures and their hydrogen molecule adsorptions are reported.

Research paper thumbnail of Study of photo-induced electron transfer in pyrene-(CH2)n-N,N′-dimethylaniline system by molecular dynamic simulation

Chemical Physics, 2008

The dynamic behavior of pyrene-(CH 2) n-N,N 0-dimethylaniline (PnD; n = 1-3) in acetonitrile and ... more The dynamic behavior of pyrene-(CH 2) n-N,N 0-dimethylaniline (PnD; n = 1-3) in acetonitrile and cyclohexane was investigated with molecular dynamic simulation (MD). Then, changes in distance (R) between pyrene and N,N-dimethylaniline moieties with time were obtained at time intervals of 1 ps for P3D, 0.1 ps for P2D and 0.02 ps for P1D. Photo-induced electron transfer (ET) rates were evaluated with Kakitani, Yoshimori and Mataga theory (KYM theory) with R at each time. The observed fluorescence intensities with lifetimes, 11 ps for P3D, 6.1 ps for P2D and 1.7 ps for P1D were obtained from observed rise times of transient absorbance of pyrene anion radicals in PnD in acetonitrile. Parameters contained in KYM theory, frequency factor (m 0), coefficient for criterion of adiabatic and nonadiabatic processes (b), critical distance between adiabatic and non-adiabatic processes (R 0) and standard free energy change (DG 0) were determined by a non-linear least squares method, so as to fit the calculated fluorescence intensities obtained with the observed fluorescence intensities. The calculated intensities were in good agreement with the observed ones. The values of best-fit parameters, m 0 , b, R 0 , and DG 0 were 82.04 ps À1 , 5.56 nm À1 , 0.568 nm and À2.12 eV, respectively, in P3D, 82.05 ps À1 , 5.56 nm À1 , 0.569 nm and À2.12 eV, respectively, for P2D, and 93.19 ps À1 , 5.58 nm À1 , 0.698 nm and À2.08 eV, respectively, for P1D. In all systems, the ET processes were non-adiabatic. The dependence of ET rate on R were calculated with these parameters, which suggests that ET rate also exhibits a ''bell shape", such as the one obtained in the variation of DG 0. Therefore, ET rate may decrease with R less than 0.55 nm for all PnD (n = 1-3) systems.

Research paper thumbnail of Molecular structures of 3, 6-di (hexylthioureido) acridine conformers, their protonation, 1H NMR and IR analyses: Theoretical and experimental studies

Journal of molecular …, 2007

The optimized structures of the 3,6-di(hexylthioureido)acridine conformers were obtained using de... more The optimized structures of the 3,6-di(hexylthioureido)acridine conformers were obtained using density functional theory (DFT) and ONIOM methods. Three conformers of 3,6-di(hexylthioureido )acridine and their corresponding protonated forms were found. Single-point energies ...

Research paper thumbnail of Optical chemosensors for Cu(II) ion based on BODIPY derivatives: an experimental and theoretical study

Journal of Molecular Modeling, 2013

Two BODIPY derivatives for Cu(2+) ion chemosensors containing 4-[2-(diethylamino)-2-oxoethoxy]phe... more Two BODIPY derivatives for Cu(2+) ion chemosensors containing 4-[2-(diethylamino)-2-oxoethoxy]phenyl (BDP1) and 3,4-bis[2-(diethylamino)-2-oxoethoxy]phenyl (BDP2) were synthesized by coupling appropriate N,N-diethyl-2-(4-formylphenoxy)acetamide and 2,4-dimethylpyrrole moieties in the presence of trifluoroacetic acid and anhydrous dichloromethane at room temperature. The binding abilities between these chemosensors and 50 equivalents of Na(+), K(+), Ag(+), Ca(2+), Fe(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+) ions were studied using UV-vis and fluorescence spectrophotometry. The results show that, compared to other ions, both the UV-vis absorption and fluorescence emission intensity of BDP2 decreased dramatically when Cu(2+) ion was added. To explain this behavior, ab initio quantum chemical calculations were performed using correlated second-order Møller-Plesset perturbation theory (MP2/LanL2DZ). The calculated orbital energies indicated that the decrease in UV-vis absorption intensity and the quenching of fluorescene emission were due to the single-electron reduction of Cu(2+) to Cu(+) ion.

Research paper thumbnail of Spray coating thin polymeric sensor films for Au 3+

Journal of Applied Polymer Science

Research paper thumbnail of Novel selective and sensitive optical chemosensor based on phenylfluorone derivative for detection of Ge(IV) ion in aqueous solution

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2018

A water soluble chemosensor for Ge ion based on fluorone derivative containing 3,4-bis(2-(diethyl... more A water soluble chemosensor for Ge ion based on fluorone derivative containing 3,4-bis(2-(diethylamino)-2-oxoethoxy)phenyl (R8) has been synthesized. The binding abilities between R8 and 10 equiv. of Na, K, Ca, Fe, Cu, Cd, Hg, Pb, Al, Cr, Fe and Ge ions in 1% v/v EtOH-water (tris-buffer pH 7.0) were studied using UV-vis and fluorescence spectrophotometry. When observed by naked-eyes, the color of R8 changed from yellow-orange to pink and the fluorescent color changed from green to non-fluorescence when complexed with Ge ion. The spectral analysis showed that UV-vis absorption and fluorescence emission intensity of R8 decreased dramatically when Ge ion was added comparing with other ions. To explain this behavior, the quantum calculation was performed using the hybrid density functional at B3LYP /LanL2DZ level of theory. The calculated orbital energies indicated that the decreasing of UV-vis absorption and the quenching of fluorescence were due to the complexation induced metal to li...

Research paper thumbnail of Synthesis of electrochemical and optical anion sensors containing organic dyes

Thesis (Ph.D.)--Chulalongkorn University, 2006 Six chromo-and fluorogenic anion sensors have been... more Thesis (Ph.D.)--Chulalongkorn University, 2006 Six chromo-and fluorogenic anion sensors have been synthesized by coupling the appropriate dithioisocyanate of anthracene derivatives with hexylamine in dichloromethane. The anthracene moieties acted as signaling units and thiourea moieties as binding sites. Anions binding properties of synthetic sensors have been studied by [superscript 1]H-NMR titration (10 mM in DMSO-d[subscript 6] and the 1:1 complexations were confirmed by Job's plots. Compounds L1 and L4 formed the most stable complexes with pimelate. Compounds L3 and L5 formed the most stable complexes with glutarate. Compound L2 formed the most stable complexes with succinate. Binding constants were, therefore, found to be strongly dependent on the chain length of dicarboxylate anions and the distance between thiourea groups. UV-vis titrations of all compounds (0.02 mM in DMSO) showed decreasing of maxima absorption intensity when successive addition of dicarboxylate anions....

Research paper thumbnail of Fluoride Recognition of Amide-and Pyrrole-Based Receptors: A Theoretical Study

The novel amide-based receptors, N-(anthracen-1-yl)-1H-pyrrole-2-carboxamide (1) and N-(8-(1H-pyr... more The novel amide-based receptors, N-(anthracen-1-yl)-1H-pyrrole-2-carboxamide (1) and N-(8-(1H-pyrrole-2-carboxamido) anthracen-1-yl)-1H-pyrrole-2-carboxamide (2) have been designed and investigated for their halide ion recognition using the density functional theory calculations in gas and solvent phases. Electronic and thermodynamic properties of halide ion binding complexes of receptors were investigated. Intermolecular interactions in all the studied complexes occurring via hydrogen bonding are found. The designed receptors 1 and 2 are found to be excellent selectivity for fluoride ion in both gas and solvent phases.

Research paper thumbnail of A density functional investigation of 1,3-bis(4-nitrophenyl)urea as anion receptor

The B3LYP/6-311+G(d,p) optimized structures of 1,3-bis(4-nitrophenyl)urea receptor (1) and its co... more The B3LYP/6-311+G(d,p) optimized structures of 1,3-bis(4-nitrophenyl)urea receptor (1) and its complexes with halide ions F À , Cl À , Br À , oxygen-containing anions NO À 2 , NO À 3 , HCO À 3 , HSO À 4 , H 2 PO À 4 , CH 3 COO À and C 6 H 5 COO À ions were obtained. Binding energies and thermodynamic properties of binding between the receptor 1 and these anions were determined. Binding energies of receptor 1 are in decreasing orders: CH 3 COO À > HCO 3 À $ C 6 H 5 COO À > NO À 2 > H 2 PO À 4 > NO À 3 > HSO À 4 for oxygen-containing anions and F À > Cl À > Br À for halide ions. It was found that the binding energies depend on their hydrogen-bond distances of their binding atoms. It was also found that the complexes of receptor 1 and the studied anions are formed via two-point hydrogen-bonding interactions.

Research paper thumbnail of A theoretical investigation on structures of tripodal thiourea derivatives and their anion recognition

Structural Chemistry, 2011

... authorized users. W. Rakrai Á N. Morakot Á B. Wanno Center of Excellence for Innovation in Ch... more ... authorized users. W. Rakrai Á N. Morakot Á B. Wanno Center of Excellence for Innovation in Chemistry and Department of Chemistry, Faculty of Science, Mahasarakham University, Mahasarakham 44150, Thailand S. Keawwangchai ...

Research paper thumbnail of Quantum chemical investigation on structures of pyrrolic amides functionalized (5,5) single-walled carbon nanotube and their binding with halide ions

Structural Chemistry, 2012

Abstract The structures of mono-and di-podal pyrrolic amides functionalized (5, 5) single-walled ... more Abstract The structures of mono-and di-podal pyrrolic amides functionalized (5, 5) single-walled carbon nanotubes (SWCNTs) and their complexes with fluoride, chloride, and bromide ions were obtained using the two-layered ONIOM (MO: MO) and density ...

Research paper thumbnail of Design and synthesis of thiourea based receptor containing naphthalene as oxalate selective sensor

Journal of Molecular Modeling, 2010

The thiourea based receptor containing naphthalene groups (1), has been successfully designed and... more The thiourea based receptor containing naphthalene groups (1), has been successfully designed and synthesized for application as an oxalate receptor. A density functional theory at B3LYP/6-31G(d,p) level of theory has been applied to predict the binding ability between 1 and selected anions, i.e., oxalate, malonate, succinate, glutarate, dihydrogen phosphate, and hydrogen sulphate. Calculation results point out that receptor 1 shows the strongest interaction to oxalate ion with the binding free energy of 172.48 kcal mol −1. The recognition ability of 1 to the selected anions has been also investigated by means of the absorption and emission techniques. Experimental results are in excellent agreement with the calculation data in which receptor 1 shows highly selective for oxalate ion over the other anions with logβ of 3.82 (0.02) M −1 by means of the size of binding cavity.

Research paper thumbnail of Gas adsorption on the Zn–, Pd– and Os–doped armchair (5,5) single–walled carbon nanotubes

Journal of Molecular Modeling, 2012

The adsorption of NO 2 , NH 3 , H 2 O, CO 2 and H 2 gases on the undoped, Zn-, Pd-and Os-doped ar... more The adsorption of NO 2 , NH 3 , H 2 O, CO 2 and H 2 gases on the undoped, Zn-, Pd-and Os-doped armchair (5,5) single-walled carbon nanotubes (SWCNTs) were studied using density functional method. The adsorptions of these five gases on the Zn-, Pd-and Os-doped SWCNTs are obviously stronger than on the undoped SWCNT and their adsorption abilities are in the same order: NO 2 > NH 3 > H 2 O > CO 2 > H 2. Adsorption energies for all the studied gases on the undoped, Zn-, Pd-and Os-doped SWCNTs computed at the B3LYP/LanL2DZ level are reported.

Research paper thumbnail of Density functional investigation of hydrogen gas adsorption on Fe−doped pristine and Stone−Wales defected single−walled carbon nanotubes

Journal of Molecular Modeling, 2012

The adsorptions of hydrogen molecule of the Fe - doped pristine and Stone - Wales defected armcha... more The adsorptions of hydrogen molecule of the Fe - doped pristine and Stone - Wales defected armchair (5,5) single - walled carbon nanotubes (SWCNTs) compared with the pristine SWCNT were investigated by using the density functional theory at the B3LYP/LanL2DZ level. The doping of Fe atom into SWCNTs occurring via an exothermic process was found. The adsorptions of hydrogen molecule on the Fe - doped structures of either perfect or SW defected SWCNTs are stronger than on their corresponding undoped structures. The structural and electronic properties of the pristine and SW defected SWCNTs, their Fe - doped structures and their hydrogen molecule adsorptions are reported.

Research paper thumbnail of Study of photo-induced electron transfer in pyrene-(CH2)n-N,N′-dimethylaniline system by molecular dynamic simulation

Chemical Physics, 2008

The dynamic behavior of pyrene-(CH 2) n-N,N 0-dimethylaniline (PnD; n = 1-3) in acetonitrile and ... more The dynamic behavior of pyrene-(CH 2) n-N,N 0-dimethylaniline (PnD; n = 1-3) in acetonitrile and cyclohexane was investigated with molecular dynamic simulation (MD). Then, changes in distance (R) between pyrene and N,N-dimethylaniline moieties with time were obtained at time intervals of 1 ps for P3D, 0.1 ps for P2D and 0.02 ps for P1D. Photo-induced electron transfer (ET) rates were evaluated with Kakitani, Yoshimori and Mataga theory (KYM theory) with R at each time. The observed fluorescence intensities with lifetimes, 11 ps for P3D, 6.1 ps for P2D and 1.7 ps for P1D were obtained from observed rise times of transient absorbance of pyrene anion radicals in PnD in acetonitrile. Parameters contained in KYM theory, frequency factor (m 0), coefficient for criterion of adiabatic and nonadiabatic processes (b), critical distance between adiabatic and non-adiabatic processes (R 0) and standard free energy change (DG 0) were determined by a non-linear least squares method, so as to fit the calculated fluorescence intensities obtained with the observed fluorescence intensities. The calculated intensities were in good agreement with the observed ones. The values of best-fit parameters, m 0 , b, R 0 , and DG 0 were 82.04 ps À1 , 5.56 nm À1 , 0.568 nm and À2.12 eV, respectively, in P3D, 82.05 ps À1 , 5.56 nm À1 , 0.569 nm and À2.12 eV, respectively, for P2D, and 93.19 ps À1 , 5.58 nm À1 , 0.698 nm and À2.08 eV, respectively, for P1D. In all systems, the ET processes were non-adiabatic. The dependence of ET rate on R were calculated with these parameters, which suggests that ET rate also exhibits a ''bell shape", such as the one obtained in the variation of DG 0. Therefore, ET rate may decrease with R less than 0.55 nm for all PnD (n = 1-3) systems.

Research paper thumbnail of Molecular structures of 3, 6-di (hexylthioureido) acridine conformers, their protonation, 1H NMR and IR analyses: Theoretical and experimental studies

Journal of molecular …, 2007

The optimized structures of the 3,6-di(hexylthioureido)acridine conformers were obtained using de... more The optimized structures of the 3,6-di(hexylthioureido)acridine conformers were obtained using density functional theory (DFT) and ONIOM methods. Three conformers of 3,6-di(hexylthioureido )acridine and their corresponding protonated forms were found. Single-point energies ...

Research paper thumbnail of Optical chemosensors for Cu(II) ion based on BODIPY derivatives: an experimental and theoretical study

Journal of Molecular Modeling, 2013

Two BODIPY derivatives for Cu(2+) ion chemosensors containing 4-[2-(diethylamino)-2-oxoethoxy]phe... more Two BODIPY derivatives for Cu(2+) ion chemosensors containing 4-[2-(diethylamino)-2-oxoethoxy]phenyl (BDP1) and 3,4-bis[2-(diethylamino)-2-oxoethoxy]phenyl (BDP2) were synthesized by coupling appropriate N,N-diethyl-2-(4-formylphenoxy)acetamide and 2,4-dimethylpyrrole moieties in the presence of trifluoroacetic acid and anhydrous dichloromethane at room temperature. The binding abilities between these chemosensors and 50 equivalents of Na(+), K(+), Ag(+), Ca(2+), Fe(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+) ions were studied using UV-vis and fluorescence spectrophotometry. The results show that, compared to other ions, both the UV-vis absorption and fluorescence emission intensity of BDP2 decreased dramatically when Cu(2+) ion was added. To explain this behavior, ab initio quantum chemical calculations were performed using correlated second-order Møller-Plesset perturbation theory (MP2/LanL2DZ). The calculated orbital energies indicated that the decrease in UV-vis absorption intensity and the quenching of fluorescene emission were due to the single-electron reduction of Cu(2+) to Cu(+) ion.