Excited state substituent constants: to Hammett or not?

How the Substituent Effect Influences π-Electron Delocalisation in the Ring of Reactants in the Reaction Defining the Hammett Substituent Constants σm and σp

Application of the geometry (HOMA, EN, GEO) and magnetism based (NICS, NICS(1)) indices of aromaticity to optimised geometry of the ring in 12 meta – and 12 para – substituted benzoic acids and their anions by use of DFT computations at B3LYP/6-311+G(d,p) level has shown a very low substituent effect on the π-electron delocalisation. This resembles (qualitatively) the resistance of benzene (and...

State-to-state rate constants for collision induced energy transfer of electronically excited NH2 with NH3

Collisional energy transfer of NH2 in its electronically excited state à A1 is investigated with time-resolved Fourier transform emission spectroscopy. NH2 is produced by photodissociation of NH3 and relaxed to low rotational levels before excitation into the electronically excited state. Originating from collisions with NH3 , rate constants for total collisional removal and state-to-state rate...

The Use of Hammett Constants to Understand the Non-Covalent Binding of Aromatics

Non-covalent interactions of aromatics are important in a wide range of chemical and biological applications. The past two decades have seen numerous reports of arene-arene binding being understood in terms Hammett substituent constants, and similar analyses have recently been extended to cation-arene and anion-arene binding. It is not immediately clear why electrostatic Hammett parameters shou...

Comparative Study of Excited State Dipole Moment of Coumarin Laser Dyes: Solvent and Substituent Effect

In the present work, an array of novel substituted 2H-chromen-2-one (coumarin derivatives abbreviated as C-337, C-480, C-540A) has been subjected to photophysical analysis. Although the influence of the electron donating groups such as amino, substituted amino, hydroxyl, alkoxy groups at position 7 of the coumarin ring system has been extensively studied, However, coumarin moieties with substit...

Folic Acid Supplementation: to Advise or not to Advise?