the potential function of lippincott and schroeder for linear hydrogen bond has been re-examined and extended to nonlinear hydrogen bond. the parameters originally introduced to the potential function by lippincott and schroeder have been determined from the structural parameters such as 0.. .odistance 0-h bond distance, h.. .o distance and hoo angle. thevalidity of harmonic oscillator approxim...

A (1) (TS) J F,H(O) coupling pathway, dictated by a hydrogen bond, in some 2-fluorobenzoic acids has been observed, while such an interaction does not occur in 2-fluorophenol. Thus, this work reports the conformational analysis of 2-fluorophenylboronic acid (1), in order to evaluate a possible intramolecular OH∙∙∙F hydrogen bond in comparison to an nF→pB interaction, which mimics the quantum nF...

Halogen bonds are shown to possess the same characteristics as hydrogen bonds: charge transfer, resonance assistance and cooperativity. This follows from the computational analyses of the structure and bonding in N-halo-base pairs and quartets. The objective was to achieve an understanding of the nature of resonance-assisted halogen bonds (RAXB): how they resemble or differ from the better unde...

We present the resonant two-photon ionization (R2PI) spectra as well as the UV–UV and IR–UV double resonance spectra for the cyclic dipeptide Phe-Ser. The R2PI spectrum shows five strong transitions in the region of 37 500–37 900 cm . By performing UV–UV double resonance spectroscopy, we distinguished 5 different conformers. For each of these conformers, the origin is the most intense transitio...

As part of a programme of work to extend central-group coverage in the Cambridge Crystallographic Data Centre's (CCDC) IsoStar knowledge base of intermolecular interactions, we have studied the hydrogen-bonding abilities of squaric acid (H2SQ) and its mono- and dianions (HSQ(-) and SQ(2-)) using the Cambridge Structural Database (CSD) along with dispersion-corrected density functional theory (D...

Local stretching modes for 69 different DH single bonds and 58 H· · ·A H-bonds are calculated at the ωB97X-D/aug-cc-pVTZ level of theory to describe the changes in donor D and acceptor A upon forming the hydrogen-bonded complex. The intrinsic strength of the DH and AH interactions is determined utilizing the properties of a well-defined set of local, uncoupled vibrational modes. The local mode ...

The photophysics of a prospective drug molecule, 3,5-diiodosalicylic acid (3,5-DISA), having a wide spectrum of biological and medicinal applications, have been investigated using spectroscopic techniques and computational analyses. The remarkably large Stokes' shifts in various solvents from 3,5-DISA has been intertwined with the occurrence of an excited-state intramolecular proton transfer (E...

The potential function of Lippincott and Schroeder for linear hydrogen bond has been re-examined and extended to nonlinear hydrogen bond. The parameters originally introduced to the potential function by Lippincott and Schroeder have been determined from the structural parameters such as 0.. .Odistance 0-H bond distance, H.. .O distance and HOO angle. Thevalidity of harmonic oscillator appr...

human serum albumin (hsa) is the most abundant protein constituent of blood plasma. this protein consists of a single polypeptide chain of 585 amino acid residues, which has many important physiological functions. hsa can bind and carry many drugs, including anticoagulants, tranquilizers, and general anesthetics. some technique such as: fluorescence spectroscopy, three-dimensional fluorescence ...

Molecular structure, isomerism, conformational stability and intramolecular hydrogen bonding (IHB) of cis-enol forms of 1-(n-pyridyl)butane-1,3-diones (nPBD) (n = 2, 3, or 4) have been investigated by means of density functional theory (DFT) calculations. Energy differences for all possible nPBD cis-enol forms of isomers with respect to the most stable form of the correspondin...