Solvent effect on the vibrational spectrum of Michler's ketone. Experimental and theoretical investigations

Michler's Ketone: β-Cyclodextrin Host-Guest Inclusion Complex for Enhancing the Ultraviolet Protection Factor of Poplin Cotton Fabric

Michler's ketone (4,4' bis(N,N-dimethylamino)benzophenone) mk is a potential ultraviolet radiation (UVR) absorber in various materials. In this report, we have tested the UVR filtering ability of mk on cotton fabric. The beta-cyclodextrin (β-CD) inclusion complex of mk enhances ultraviolet protection factor (UPF) drastically. The impact of β-CD on the UVR filtering of mk are demonstrated by investigating the guest (mk:absorbers)-host (β-CD:enhancer) inclusion complex. Spectral and molecular docking analysis of mk:β-CD complex infers the vertical insertion of the guest molecule by positioning -C=O group of mk at the center of the host molecule with the exclusion of the terminal atoms of guest molecule outside the β-CD cavity. Thus, the host; β-CD renders an inflexible fit to the guest:mk. The inflexible fit of mk into the β-CD cavity enhances the UVR dissipation when it is incorporated on the poplin cotton fabric. With UPF =46 mk:β-CD complex is proposed as a potential UVR absorber suitable for manufacturing sun protective textiles. The holding of mk by β-CD enhances the UVR dissipation and hence facilitates the native red-shifted emission and non-radiative relaxation by the formation of twisted intramolecular charge transfer in mk.

Molecular, vibrational and electronic structure of 4-bromo-2-halogenobenzaldehydes: Halogen and solvent effects

The halogen and solvent effects on the structure of 4-bromo-2-halogenobenzaldehydes [C

Photochemical Energy Storage and Electrochemically Triggered Energy Release in the Norbornadiene-Quadricyclane System: UV Photochemistry and IR Spectroelectrochemistry in a Combined Experiment

The two valence isomers norbornadiene (NBD) and quadricyclane (QC) enable solar energy storage in a single molecule system. We present a new photoelectrochemical infrared reflection absorption spectroscopy (PEC-IRRAS) experiment, which allows monitoring of the complete energy storage and release cycle by in situ vibrational spectroscopy. Both processes were investigated, the photochemical conversion from NBD to QC using the photosensitizer 4,4'-bis(dimethylamino)benzophenone (Michler's ketone, MK) and the electrochemically triggered cycloreversion from QC to NBD. Photochemical conversion was obtained with characteristic conversion times on the order of 500 ms. All experiments were performed under full potential control in a thin-layer configuration with a Pt(111) working electrode. The vibrational spectra of NBD, QC, and MK were analyzed in the fingerprint region, permitting quantitative analysis of the spectroscopic data. We determined selectivities for both the photochemical conversion and the electrochemical cycloreversion and identified the critical steps that limit the reversibility of the storage cycle.

Halogen and solvent effects on the conformational, vibrational and electronic properties of 1,4-diformylpiperazine: A combined experimental and DFT study

The molecular structure and properties of 1,4-diformylpiperazine (1,4-dfp, C6H[Formula: see text]N2O2) were investigated by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy and density functional theory (DFT). The Becke-3-Lee–Yang–Parr (B3LYP) functional was used with the 6-31[Formula: see text]G(d,p) basis set. Total energy distribution (TED) analysis of normal modes was performed to identify characteristic frequencies by the scaled quantum mechanical (SQM) method. Halogeno-analogs of 1,4-dfp were studied to understand the halogen effect. Computations were focused on five conformational isomers of the compounds in the gas phase and in solutions. The computed and experimental frequencies of the C[Formula: see text]O stretching vibration of 1,4-dfp were correlated with the empirical solvent parameters such as the Kirkwood–Bauer–Magat (KBM) equation, the solvent acceptor number (AN), Swain parameters and linear solvation energy relationships (LSER). The electronic properties of the compounds were also examined. The findings from the present work may be useful to understand systems involving the halogens and conformational changes analogous to the compounds investigated.

Conformation stability, halogen and solvent effects on CO stretching of 4-chloro-3-halogenobenzaldehydes

The effects of halogen and solvent on the conformation and carbonyl stretching of 4-chloro-3-halogenobenzaldehydes [C7H4ClXO; X=F (CFB), Cl (CCB) or Br (CBB)] were investigated using the density functional theory (DFT) method. The B3LYP functional was used by the 6-311+G(3df,p) basis set in combination with the polarizable continuum model (PCM). Computations were focused on the cis and trans isomers of the compounds in 18 different polar or non-polar organic solvents. The theoretical frequencies of the solvent-induced CO stretching vibrations were correlated with the empirical solvent parameters such as the Kirkwood-Bauer-Magat (KBM) equation, the solvent acceptor number (AN), Swain parameters and the linear solvation energy relationships (LSER). The present work explores the effect of both the halogen and medium on the conformational preference and CO vibrational frequency. The findings of this work can be useful to those systems involving changes in the conformations analogous to the compounds studied.