Conformational Preference Determined by C–H···π Interaction of an O–H···O Hydrogen-Bonded Binary Complex of p-Fluorophenol with 2,5-Dihydrofuran: A Laser-Induced Fluorescence Spectroscopy Study

Abstract

Conformational preferences of a binary hydrogen-bonded complex between p-fluorophenol (pFP) and 2,5-dihydrofuran (DHF) have been studied by means of laser induced fluorescence (LIF) spectroscopy in a supersonic jet expansion. Calculation predicts two major conformers for this complex, one having a nearly linear geometry in which the two molecular moieties are bound only by an O-H···O H-bond, but in the other an additional C-H···π type interaction between an ortho C-H group of pFP and ethylene group of DHF contributes to the binding stabilization and results in a folded geometry for the complex with respect to a global view, although the H-bond angle of the latter is relatively larger. This prediction is realized experimentally by identifying transitions corresponding to the two discrete conformers in a vibrationally resolved LIF excitation spectrum of the complex, and the red shifts of S-S origin band of pFP moiety of the two conformers are 542 and 659 cm, respectively. The assignments are corroborated by means of dispersed fluorescence (DF) spectroscopy. In comparison, the LIF spectral bands for the pFP-tetrahydrofuran complex can be corresponded to only one conformer, whose S-S origin transition shows a red shift (563 cm) somewhat similar to the linear conformer of pFP-DHF complex. Such similarities in spectral shifting behavior is consistent with the predictions of electronic structure calculations. The DF spectra also reveal that the energy threshold and pathways of vibrational dynamics in S of the two conformers show different behavior. Excitation to 6a level of pFP moiety of the folded conformer displays signatures of restricted intramolecular vibrational energy redistribution (IVR), whereas the linear form displays the emission feature for dissipative IVR.

Composite host lattices of 4,4′-sulfonyldibenzoate water/boric acid in two tetrapropylammonium inclusion compounds

“…Additionally, the O-HÁ Á ÁO hydrogen bond, which is a classical strong interaction, exists widely in the crystal structures of carboxylic acids (Mukhopadhyay et al, 2018). From an analysis of the related hydrogen bonds herein, it is found that O-HÁ Á ÁO À hydrogen bonds [2.822 (3)-2.840 (3) Å ] involving water molecules of 1 are weaker than similar hydrogen bonds in 2.…”

Ab Initio, Transition State Theory, and Kinetic Modeling Study of the HO2-Assisted Keto–Enol Tautomerism Propen-2-ol + HO2 ⇔ Acetone + HO2 under Combustion, Atmospheric, and Interstellar Conditions

“…The O–H···π hydrogen bond, and its analogues N–H···π and C–H···π, have been reported as weak interactions that induce to some stabilization − and have implications in the folding of biomolecules . However, they are not usually as strong as conventional hydrogen bonds, which is in stark contrast to our findings on Complex-1, wherein the O–H···π hydrogen bond stabilizes the complex to a larger extent.…”

“…4 The standard free energy barriers of the HO2-catalyzed and non-catalyzed tautomerisms are 17.9 and 53.64 kcal mol -1 , respectively. interactions that induce to some stabilization [35][36][37] and have implications in the folding of biomolecules. 36 However, they are not usually as strong as conventional hydrogen bonds, which is in stark contrast to our With the factors − ( ) , the rate constants for the forward and reverse reactions i-C3H5OH + HO2…”

Generalized Kohn‐Sham energy decomposition analysis and its applications

“…Understanding the physical origins of noncovalent interactions is an important task for EDA methods. GKS‐EDA and LMO‐EDA have been used to analyze various noncovalent interactions, including hydrogen bond, halogen bond, chalcogen bond, tetrel bond, pnicogen bond, π‐π stacking, cation⋯π, anion⋯π, XH⋯π (X = C, N, or O), and cooperative effects . Here we illustrate several representative applications for hydrogen bonds, halogen bonds and π‐π stacking, which show the diversity of physical origins in various noncovalent interactions.…”