Crystal structure, IR-LD spectroscopic, theoretical and vibrational analysis of valinamide ester amide of squaric acid diethyl ester

Abstract

Valinamide ester amide of squaric acid has been synthesized and structurally characterized by single crystal X-ray diffraction. Individual molecules are linked into zigzag helix chains running parallel to [0 1 0] by N-H · · · O hydrogen bonds of length 2.7908(19) Å and 2.980(2) Å involving the valinamide nitrogen atoms and the amide carbonyl oxygen atom. An experimental IR spectroscopic characterization and theoretical vibrational analysis have also been performed, using the possibilities of polarized linear-T. Kolev ( ) · E. Cherneva

Local dipole interactions induce helicity of (S)-2-butyl-N-(1,8-naphthaloyl)-2-aminobenzoate molecules containing 1,8-naphthalimide rings utilized as a column building blocks: X-ray and quantum mechanical studies

“…articles published in Structural Chemistry in the years 2005 and 2006 [13][14][15][16][17][18][19][20][21][22][23]). Calculations utilizing only HF theory, which neglects dynamic electronic correlation, were also often reported [24][25][26]. We have found one study with calculations performed exclusively at semiempirical PM3 level, which allowed the authors to investigate conformational flexibility of 2-methyl-4-(4-methoxyphenylazo) phenol [27].…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 17, 2006) and the discipline

“…In the next paper Kolev et al [273] describe synthesis and structural characterization of a mixed ethyl ester and valinamide of squaric acid as a potentially bioactive compound [274,275]. In this molecule the individual molecules are linked into zig-zag helix chains running parallel to [0 1 0] by N-HÁÁÁO hydrogen bonds involving the valinamide nitrogen atoms and the amide carbonyl oxygen atom.…”

Solid-state linear-dichroic infrared (IR-LD) spectroscopic and theoretical characterization of 2-[(2-ethoxy-3,4-dioxocyclobut-1-en-yl)amino]propanamide

“…Building on previous spectroscopic and structural studies of some optically active derivatives of amino acids with potential nonlinear optical and electro-optical properties [1,2], the crystal structures of a series of amino acid amides of squaric acid [3][4][5][6][7][8] and hydrogensquarates [9][10][11][12] have been reported. Structural studies of some C-gα-amidated amino acids (Ile, Val, Thr, Ser, Met, Trp, Gln and Arg) have been performed and compared with their C-α-unamidated counterparts [13].…”

“…These data are compared with single crystal X-ray results [8,[22][23][24][25][26][27][28][29][30] and theoretical ab initio calculations. The possibilities of this new approach have been demonstrated in a series of peptide systems [8,[22][23][24][25][26][27][28][29][30]. [8,[22][23][24][25][26][27][28][29][30].…”

“…[8,[22][23][24][25][26][27][28][29][30]. The IR-LD spectroscopy theory and the difference-reduction procedure used for polarized IR spectral interpretation are described in [8,[22][23][24][25][26][27][28][29]. The method consists in subtraction of IR s (a perpendicular spectrum, resulting from a 90…”