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Item IR spectra of CH2I2 in Ar and N2 cryomatrices: Evidence of unusual band splitting in N2 matrix(Springer, 2022-08) Chakraborty, Amrita; Chakraborty, ShamikMatrix isolation IR spectra of in matrix are analysed using IR spectra obtained in the Ar matrix, quantum chemical calculations, and molecular point group symmetry to determine the origin of the unusual splitting observed in the antisymmetric stretching (), rocking (), wagging (), and antisymmetric stretching () modes of only in matrix and not in Ar matrix. The , , , and vibrational modes belong to either or irreducible representations under point group symmetry. IR spectra in matrix is reported for the first time. IR spectra recorded in Ar matrix are consistent with previous reports. Electronic structure calculations have been performed to obtain simulated IR spectra of with and point group symmetries, conformers, [-], and [-]. IR spectra obtained in Ar and matrices originate from , , and splitting of IR peaks in matrix. Splitting of the IR peaks of in solid state is described by Davydov splitting or factor group splitting. The observed splitting of IR peaks in matrix is due to the lowering of symmetry of from to one of its sub groups due to the perturbation of the rigid matrix that possess quadrupole moment.Item Matrix isolation infrared study of complexes between Image 1 and Image 2: Evidence of formation of hydrogen bond and chalcogen bond(Elsevier, 2023-11) Chakraborty, ShamikAmong the non-covalent interactions, the most well studied is the hydrogen bonding interaction. A new type of non-covalent interaction is the chalcogen bonding interaction. In the present work 1:1 complex of [Image 3] has been characterised using matrix isolation infrared spectroscopy and electronic structure calculations. Two minima have been obtained on the dimer potential energy surface at the MP2 level of calculations with 6-311++G(d,p) and 6-311++G(3df,2pd) basis sets. One of the minima is stabilised by Image 4 hydrogen bond and the other minima is stabilised by Image 5 chalcogen bond along with secondary Image 6 hydrogen bond. Vibrational spectra in the Image 7 stretching, Image 8 stretching, and Image 7 bending modes have been monitored to understand the complex formation. The formation of the hydrogen- and chalcogen-bonded complex in Image 9 and Image 10 matrices are confirmed by comparison of the experimental and simulated vibrational frequencies. Stabilisation energy, energy decomposition analysis, natural bond orbital analysis, and atoms in molecules analysis provide insight into the nature of the interactions. This work presents the first experimental report where both the hydrogen- and chalcogen-bonded complexes are formed simultaneously. This work also provides the first impression of the Image 4 hydrogen bonding and Image 5 chalcogen bonding interaction between Image 1 and Image 2.Item Investigation of [CHCl3-CH3OH] complex using matrix-isolation IR spectroscopy and quantum chemical calculation: Evidence of hydrogen- and halogen-bonding interaction(Elsevier, 2022-03) Chakraborty, Amrita; Chakraborty, ShamikMixture of CHCl3-CH3OH is a popular non-aqueous solvent mixture that exhibits strong synergistic solvation. The specific interaction between the CHCl3 and CH3OH is investigated using 1:1 complex in N2 matrix along with electronic structure calculation. Three different type of interactions are possible between CHCl3 and CH3OH at the molecular level: C-HO hydrogen bond, O-HCl hydrogen bond, and C-ClO halogen bond. One C-HO hydrogen bond minimum, two O-HCl hydrogen bond minima, and one C-ClO halogen bond minimum are obtained on the [CHCl3-CH3OH] dimer potential energy surface. Formation of C-HO hydrogen bonded and C-ClO halogen bonded 1:1 complex of [CHCl3-CH3OH] in N2 matrix is confirmed using experimental and simulated IR spectra. The outcome of the current work would help to explain the specific interactions present in CHCl3 and CH3OH binary solvent mixture and to estimate the responses of such non-aqueous solvent mixture.Item Matrix-isolation FTIR spectroscopic study and quantum chemical calculations of 1:1 adduct of CHCl3 and C2H5OH in N2 matrix(Elsevier, 2024-06) Chakraborty, Amrita; Chakraborty, Shamik[Image 1-Image 2] mixture is a common binary solvent used in industries, organic synthesis, lipid extraction, drug extraction, etc. The purpose of this study is to have a molecular level understanding of the interaction of Image 1 with Image 2. The experiments have been carried out in low temperature Image 3 matrix using Fourier Transform Infrared spectroscopy. Electronic structure calculations have been performed to identify the possible binding motifs between Image 1 and Image 2. Three minima have been obtained on the dimer potential energy surface stabilised by Image 4 and Image 5 hydrogen bond, and Image 6 halogen bond interactions. Formation of more than one complexes have been confirmed using the experimental and simulated IR spectra. Energy decomposition analysis and Natural bond orbital analysis have been performed to understand the nature of interaction and the driving force for complexation. This is one of the first reports where separate complexes have been identified between Image 1 and anti and gauche conformers of Image 2 in the low temperature matrix.Item Infrared and electronic spectra of microhydrated para-dichlorobenzene cluster cations(Elsiever, 2010-01) Chakraborty, ShamikMicrohydrated para-dichlorobenzene cation clusters, pDCB+single bond(H2O)n with n = 1 and 2, were characterised in the electronic ground state by infrared photodissociation spectroscopy in the O–H and C–H stretch ranges and B3LYP/6–311++G∗∗ calculations. The intermolecular pDCB+single bondH2O potential features at least two nonequivalent minima with charge-dipole configuration and comparable binding energies. The pDCB+single bond(H2O)2 spectrum reveals the presence of two types of isomers, in which either a (H2O)2 dimer or two single H2O ligands are attached to pDCB+. The detected pDCB+single bond(H2O)1,2 complexes are unreactive with respect to nucleophilic substitution. This conclusion is supported for pDCB+single bondH2O by the electronic spectrum of its B ← X transition.