Experimentally measured permanent dipoles induced by hydrogen bonding. The Stark spectrum of indole–NH3

Abstract

Hydrogen bond pairs involving the chromophore indole have been extensively studied in the gas phase. Here, we report high resolution electronic spectroscopy experiments on the indole-NH(3) hydrogen bond pair in the absence and presence of an electric field. The S(1)-S(0) origin band of this complex recorded in zero field at high resolution reveals two overlapping spectra; a consequence of NH(3) hindered internal rotation. The barrier to internal rotation is predicted by theory to be less than 20 cm(-1) in the ground state, therefore requiring a non-rigid rotor Hamiltonian to interpret the spectra. Conducting the experiment in the presence of an applied electric field further perturbs the already congested spectrum of the complex, but makes possible the measurement of the permanent electric dipole moments in its S(0) and S(1) states. These values reveal significant changes in electron distribution that arise from hydrogen bonding effects.

Water-mediated correlations in DNA-enzyme interactions

“…Here we use the values and principal directions of the polarizability tensors based on the experimental and theoretical calculations for indole [20], phenol [21], and benzene [22–24], to represent the polarizability tensors of the amino acids tryptophan, tyrosine, and phenylalanine, respectively, because each ring structure defines the aromaticity of the corresponding amino acid in which it is contained. Figure 4 illustrates the orientation geometries of the principal directions and the molecular centers used in calculating the dipole displacement coordinates between aromatic amino acids in the aromatic coordinate frame.…”

“…In other words, the time average of the polarization P n along any direction n must vanish. In order to show that this is indeed the case, let us introduce the notation (18) where A 0 (t), A 1 (t), δ 0 (t), and δ 1,m (t) are real quantities and ω 0 ≡ 1/I (in natural units), where I is the average moment of inertia of the water molecule. * Note that ω 0 is also the eigenvalue of L 2 /2I on the state (1, m), with L denoting the total angular momentum for the molecule.…”

“…Polarizabilities for aromatic amino acids[18][19][20][21][22], in units of 1 au = 1.64878 × 10 −41 C 2 m 2 J −1 ,…”

Anesthetic Alterations of Collective Terahertz Oscillations in Tubulin Correlate with Clinical Potency: Implications for Anesthetic Action and Post-Operative Cognitive Dysfunction

“…Following Kurian et al . 57 , 58 , the polarizability tensors of indole 89 , phenol 90 , and benzene 91 – 93 were used to represent the polarizability tensors of the amino acids tryptophan, tyrosine, and phenylalanine, respectively. Polarizability tensors for the anesthetics, non-anesthetics and convulsants were determined as described above.…”

Water Bridging Dynamics of Polymerase Chain Reaction in the Gauge Theory Paradigm of Quantum Fields

“…Aromatic amino acid polarizabilities[40][41][42][43][44], in units of 1 au = 1.64878× 10 −41 C 2 m 2 J −1 , with α = α 2 xx + α 2 yy + α 2 zz .Reproduced from Ref [1][2],.…”