Various indolylmaleimides (IMs) were synthesized, and their fluorescence (FL) and chemiluminescence (CL) were measured. The substitution at the 2-position of the indole ring and the 3- or 4-position of the maleimide moiety caused an obvious change in the FL and CL of the IMs. An almost on-off switching of the FL of the IMs was observed. The intramolecular charge transfer from the indole moiety to the maleimide moiety occurred in 3-(1H-3-indolyl)-2,5-dihydro-1H-2,5-pyrroledione. In the FL of the IMs, CASPT2 calculations showed deprotonation of the NH group of the indole ring and the maleimide moiety at the excited state. The C[double bond, length as m-dash]C bond in the maleimide moiety was needed for strong CL in the IMs without substitution at the 2-position of the indole ring. The relationships between the FL or CL properties and the structures of the IMs were clarified. These results provide significant information on the rational design of IMs as FL and CL probes.

reaction is important in understanding the production mechanisms of anionic molecules in interstellar environments. Herein, the rate coefficients for the H − + C 2 H 2 → H 2 + C 2 H − reaction were calculated using ring-polymer molecular dynamics (RPMD), classical molecular dynamics (MD), and quasi-classical trajectory (QCT) approaches on a newly developed ab initio potential energy surface (PES) in full dimensions. PES was constructed by fitting a large number of ab initio energy points and their gradients using the permutationally invariant polynomial basis set method. There was no barrier in the reaction coordinates, which was a collinear-dominated reaction, and the reaction proceeded exothermically. It is found that the fitted PES provides the appropriate thermal rate coefficients based on all RPMD, classical MD, and QCT simulations at higher temperatures. The evaluation of the rate coefficients at lower temperatures should be conducted carefully because the fitting of the PES associated with the long-range interaction should be further improved. The spatial distribution of the nucleus allows a more effective attraction between the reactants.

Quantum phenomena are quite often of critical importance in chemical reactions. Thus the development of quantum molecular dynamics approaches is required to study the role of quantum effects such as tunnelling in chemical processes. The basis expansion leaping multi-configuration Gaussian (BEL MCG) method has been developed to obtain time-propagated wave packets describing reactive molecular systems. Here we examine the applicability of BEL MCG to double well problems in several dimensions. We pay particular attention to what is required to yield highly accurate dynamics with respect to several key features of the BEL MCG propagation. The importance of using basis functions of a width appropriate to the nature of the potential energy surface in the region of configuration space where each basis function is located is highlighted, which has implications for virtually all quantum molecular dynamics methods utilising Gaussian basis functions.