The structure of 2-methylpropanal molecule in the S1 lowest excited singlet electronic state: theoretical and experimental studies

Foreword

“…(i) Synthesis and structure studies of novel compounds, which, depending on the phase state of the substance, are carried out with the use of NMR, infrared absorption or Raman spectroscopy, as well as single-crystal x-ray diffractometry, and either assisted or not by semiempirical or nonempirical modeling, which helps in determining the role of diverse intra-and interparticle interactions that govern the formation of particular conformers or supramolecular ensembles, frameworks, and crystals [1][2][3][4][5]; (ii) Synthesis of drugs, drug precursors, and other kinds of biologically active compounds and their biological testing with the use of different experimental spectral techniques supplemented with molecular modeling that provides tentative ideas about the underlying mechanisms of biological effects [6,7]; (iii) Clarifying details of the mechanisms of important biochemical processes at the most reliable level accessible in modern simulations, namely with the use of combined quantum/classical models where the reaction site is described at the high quantum chemical level, while the effect of substantially extended dynamic neighborhood is taken into account as a properly tuned force field [8]; (iv) Determining structure peculiarities and the possible catalytic activity of different immobilized or deposited atomic layers or nano-sized particles depending on the characteristics of substrates, which is of primary importance in view of the production of more efficient and relatively cheap catalysts [9,10]; (v) Investigation of possible conformers of the compounds with complex either flexible or, by contrast, strained structures with an emphasis on the methods that provide reliable description of such compounds and the effects produced by particular substituents, functional groups, or ligands; as well as conformational analysis of molecules in different electronic states in relation to the differences in their absorption and fluorescence spectra determined by intramolecular transformations [11][12][13]; (vi) Studying diverse molecular ensembles with the use of experimental and theoretical approaches, the latter involving either molecular dynamics or stationary nonempirical modeling, with an aim to clarify the nature and strength of intermolecular forces that stabilize particular kinds of solvation shells or local neighborhoods of foreign particles, as well as the structural kinds of dynamically changing clusters, agglomerates, and conglomerates of molecules that may be present in the bulk of liquids [14]; (vii) Discovering peculiarities of the hydrogen-bonded complexes and building blocks, which are of primary importance in the case of gas-phase, liquid, and solid systems, with an emphasis on the changes, which accompany phase transitions, and spectral fingerprints observed both in the experimental infrared absorption spectra and simulated spectra retrieved from quantum chemical calculations [15][16]...…”