title: Study of Nα-benzoyl-L-argininate ethyl ester chloride, a model compound for poly(ester amide) precursors: x-ray diffraction, infrared and Raman spectroscopies, and quantum chemistry calculations.
abstract: Poly(ester amide)s (PEAs) are lacking in structural and spectroscopic information. This paper reports a structural and spectroscopic characterization of N(α)-benzoyl-L-argininate ethyl ester chloride (BAEEH(+)·Cl(-)), an important amino acid derivative and an adequate PEAs' model compound. Crystals of BAEEH(+)·Cl(-) obtained by slow evaporation in an ethanol∕water mixture were studied by different complementary techniques. X-ray analysis shows that BAEEH(+)·Cl(-) crystallizes in the chiral space group P2(1). There are two symmetry independent cations (and anions) in the unit cell. The two cations have different conformations: in one of them, the angle between the least-squares planes of the phenyl ring and the guanidyl group is 5.1(2)°, and in the other the corresponding angle is 13.3(2)°. There is an extensive network of H-bonds that assembles the ions in layers parallel to the ab plane. Experimental FT-IR and Raman spectra of BAEEH(+)·Cl(-) were recorded at room temperature in the 3750-600 cm(-1) and 3380-100 cm(-1) regions, respectively, and fully assigned. Both structural and spectroscopic analysis were supported by quantum chemistry calculations based on different models (in vacuo and solid-state DFT simulations).
authors: Department of Chemical Engineering, University of Coimbra, Pólo II, Pinhal de Marrocos, Coimbra 3030-790, Portugal.
authors: A C
authors: AC
authors: Fonseca
authors: S
authors: S
authors: Jarmelo
authors: M Ramos
authors: MR
authors: Silva
authors: A M Matos
authors: AM
authors: Beja
authors: R
authors: R
authors: Fausto
authors: M H
authors: MH
authors: Gil
authors: P N
authors: PN
authors: Simões
mesh_terms: D000577:Amides / Q000737:chemistry; D001120:Arginine / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D011091:Polyesters / Q000737:chemistry; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D014961:X-Ray Diffraction
chemical_list: D000577:Amides; C551374:N(alpha)-benzoyl-L-argininate ethyl ester chloride; D011091:Polyesters; D001120:Arginine