Condensation Product of p-anisaldehyde and L-phenylalanine: Fluorescent "on-off" Sensor for Cu2+ and IMPLICATION Logic Gate.

(Z)-2-(4-methoxybenzylideneamino)-3-phenylpropanoic acid (L) synthesized by condensation of p-anisaldehyde and L-phenylalanine acts as selective fluorescent as well as voltammetric sensor for Cu2+ in 2:1 (v/v) CH3OH:H2O. The fluorescence intensity of L (λmax 425 nm) is quenched ca. 65% by Cu2+. Metal ions - Li+, Na+, K+, Al3+, Cu2+, Zn2+, Cd2+, Hg2+, Mn2+, Ni2+ and Pb2+ do not interfere. The binding constant and the detection limits were calculated to be 0.56 × 102 M-1 and 10-6 M respectively. DFT and TDDFT calculations confirmed 2:1 binding stoichiometry between L and Cu2+ obtained from fluorescence data. The interaction between L and Cu2+ is reversible for many cycles with respect to ethylenediamine tetraacetate anion (EDTA2-) which results in IMPLICATION logic gate.

Formation of Polymeric Housene Molecules of Group 15 Elements (N, P, As, and Sb): A DFT Study.

Recently, the formation of the dimeric stibahousene molecule, bis(stibahousene), has been reported. In line with the report, the formation of dimeric housene molecules with N, P, and As is examined in light of density functional theory. Moreover, the extension of the study from dimeric to tetrameric and hexameric molecules (N, P, As, and Sb) is also performed. The study supports the formation of such polymeric housene analogues.

Density Functional Study on the Adsorption of 5-Membered N-Heterocycles on B/N/BN-Doped Graphene: Coronene as a Model System.

Adsorption of seven 5-membered N-heterocycles on B/N/BN-doped graphene (with coronene as a model system) has been studied using density functional theory (DFT). The geometry of the complexes validated the involvement of both π···π stacking and N-H···π interaction in the adsorption process. The stability of the complexes is measured in terms of stabilization energy, and the results suggested that the complexes are stable enough (stabilization energies are in the range of 7.61-14.77 kcal mol-1). Studies confirmed the stability of complexes in the solvent phase too irrespective of the dielectric of the solvent. Dispersive force is the major mode of interaction in stabilizing the complexes. Natural bond orbital analysis indicated a small contribution from electrostatic and covalent interactions. Thermochemical analysis revealed that the complexation is exothermic in nature and favorable at a lower temperature. Adsorption of N-heterocycles exerts a nominal impact on the electronic properties of the undoped/doped graphene. The study presents a simple approach to introduce an arbitrary functionality to undoped/doped graphene by preserving its electronic properties.

Condensation Product of Phenylalanine and Salicylaldehyde: Fluorescent Sensor for Zn(2.).

The condensation product of phenylalanine and salicylaldehyde (L) was synthesised and characterised which was found to be selective fluorescent "off-on" sensor for Zn(2+) ion with the detection limit 10(-5) M. The sensor is free of interferences from metal ions - Na(+), K(+), Al(3+), Mn(2+), Co(2+), Ni(2+), Cu(2+), Pb(2+), Cd(2+) and Hg(2+). The Fluorescence and the UV/visible spectral data reveals a 1:1 interaction between the sensor and Zn(2+) ion with binding constant 10(8). The DFT and TDDFT calculations confirm the structures of the sensor and the sensor-Zn(2+) complex.

Chiral modification of copper exchanged zeolite-Y with cinchonidine and its application in the asymmetric Henry reaction.

Chirally modified Cu(2+) exchanged zeolite-Y was synthesized by direct adsorption of cinchonidine under ambient conditions. The chirally modified materials were characterized using various spectrochemical and physicochemical techniques viz. BET, FTIR, MAS ((1)H and (13)C NMR), XPS, SEM, cyclic voltammetry and PXRD. Characteristic peaks of cinchonidine observed in the supported materials confirmed the adsorption of cinchonidine and its coordination with the Cu(2+) active site on copper exchanged zeolite-Y. (13)C SSNMR and XPS analysis however confirmed for the half encapsulation process, only the quinoline ring of cinchonidine gets coordinated to the internal metal sites via the N atom while the quinuclidine moiety extends out of the host surface. Cinchonidine supported Cu(2+)-Y zeolites were found to exhibit good catalytic performance in the asymmetric Henry reaction. (1)H SSNMR studies also confirmed the protonation of the N atom of the quinuclidine ring during the course of the Henry reaction. Heterogeneous chiral catalysts were effective for up to two consecutive cycles. Leaching of cinchonidine after the second cycle was found to have a negative result in the catalytic performance.

A New Fluorescent "Off-On" Sensor for Al(3+) Derived from L-alanine and Salicylaldehyde.

The condensation product of L-alanine and salicylaldehyde was synthesised and characterised which was found to be selective fluorescent "on" sensor for Al(3+) ion with the detection limit 10(-6) M. The sensor is free of interferences from metal ions - Na(+), K(+), Ca(2+), Mn(2+), Co(2+), Ni(2+), Cu(2+), Pb(2+), Cd(2+), Hg(2+) and Fe(3+). The Fluorescence and the UV/visible spectral data reveals a 1:1 interaction between the sensor and Al(3+) ion with binding constant 10(4.5). The DFT and TDDFT calculations confirm the structures of the sensor and the sensor-Al(3+) complex.

Reactivity and aromaticity of nucleobases are sensitive toward external electric field.

Reactivity and aromaticity of DNA and RNA bases toward an external electric field are analyzed using density functional theory (DFT) and density functional reactivity theory (DFRT). Reactivity of the nucleobases is measured in terms of the DFT-based reactivity descriptor, such as energy of the HOMO, global hardness, electrophilicity, etc. and is observed to be sensitive toward the strength as well as direction of the applied external electric field. In addition, the reactivity pattern follows the maximum hardness and minimum electrophilicity principles. Further, aromaticity of the species is observed to be effected by the presence of an external electric field.

Biosynthesis of Ag nanoparticles using pedicellamide and its photocatalytic activity: an eco-friendly approach.

The synthesis of silver (Ag) nanoparticles using by pedicellamide (A), isolated from Piper pedicellatum C.DC leaf is demonstrated here. TEM analysis revealed that the Ag nanoparticles predominantly form spherical in shape. The compound 'A' act as a reducing, stabilizing and capping agent. The reaction mechanism was established by using density functional theory (DFT). Photocatalytic property of the Ag nanoparticles is investigated by degradation of Methyl Red (MR) dye under UV light. The kinetic, reaction mechanism and rate constant of photocatalytic degradation of MR was evaluated. The results show that Ag nanoparticles have suitable photocatalytic activity for the degradation of MR dye.

Substituent and Solvent Effects on the Absorption Spectra of Cation-π Complexes of Benzene and Borazine: A Theoretical Study.

Time-dependent density functional theory (TDDFT) has been used to predict the absorption spectra of cation-π complexes of benzene and borazine. Both polarized continuum model (PCM) and discrete solvation model (DSM) and a combined effect of PCM and DSM on the absorption spectra have been elucidated. With decrease in size of the cation, the π → π* transitions of benzene and borazine are found to undergo blue and red shift, respectively. A number of different substituents (both electron-withdrawing and electron-donating) and a range of solvents (nonpolar to polar) have been considered to understand the effect of substituent and solvents on the absorption spectra of the cation-π complexes of benzene and borazine. Red shift in the absorption spectra of benzene cation-π complexes are observed with both electron-donating groups (EDGs) and electron-withdrawing groups (EWGs). The same trend has not been observed in the case of substituted borazine cation-π complexes. The wavelength of the electronic transitions corresponding to cation-π complexes correlates well with the Hammet constants (σp and σm). This correlation indicates that the shifting of spectral lines of the cation-π complexes on substitution is due to both resonance and inductive effect. On incorporation of solvent phases, significant red or blue shifting in the absorption spectra of the complexes has been observed. Kamlet-Taft multiparametric equation has been used to explain the effect of solvent on the absorption spectra of complexes. Polarity and polarizability are observed to play an important role in the solvatochromism of the cation-π complexes.

Effect of substituent and solvent on cation-π interactions in benzene and borazine: a computational study.

A DFT and ab initio quantum chemical study has been carried out at different theoretical levels to delve into the role of the cation-π interaction within the main group metal cations (Li(+), Na(+) and K(+)), substituted benzene and borazine. The effects of electron withdrawing and electron donating groups on these non-covalent forces of interaction were also studied. The excellent correlation between Hammett constants and binding energy values indicates that the cation-π interaction is influenced by both inductive and resonance effects. Electron donating groups (EDG) such as -CH3 and -NH2 attached to benzene at the 1, 3 and 5 position and the three boron atoms of borazine were found to strengthen these interactions, while electron withdrawing groups (EWG) such as -NO2 did the reverse. These results were further substantiated by topological analysis using the quantum theory of atoms in molecules (QTAIM). The polarized continuum model (PCM) and the discrete solvation model were used to elucidate the effect of solvation on the cation-π interaction. The size of the cations and the nature of the substituents were found to influence the enthalpy and binding energy of the systems (or complex). In the gas phase, the cation-π interaction was found to be exothermic, whereas in the presence of a polar solvent the interaction was highly endothermic. Thermochemical analysis predicts the presence of thermodynamic driving forces for borazine and benzene substituted with EDG. DFT based reactivity descriptors, such as global hardness (η), chemical potential (µ) and the electrophilicity index (ω) were used to elucidate the effect of the substituent on the reactivity of the cation-π complexes.