title: pH Dependent Chiroptical Properties of (1R,2R)- and (1S,2S)-trans-Cyclohexane Diesters and Diamides from VCD, ECD, and CPL Spectroscopy.
abstract: Diesters of (1R,2R)- and (1S,2S)-cyclohexanediols and diamides of (1R,2R)- and (1S,2S)-diaminocyclohexane with p-hydroxycinnamic acid have been known for some time to exhibit intense bisignate electronic circular dichroism (ECD) spectra in CH3OH. It was also known that added NaOH causes a bathochromic shift of ∼50 nm in CH3OH, and an even higher one in DMSO. We have measured vibrational circular dichroism (VCD) spectra both for neutral compounds and in the presence of NaOH and other bases. The VCD and IR spectra in the mid-IR region for CD3OD and DMSO-d6 solution exhibit high sensitivity to the charged state for the diesters. They possess two strong bisignate features in the presence of bases in the mid-IR, which are interpreted in terms of vibrational exciton couplets, while this phenomenon is less evident in diamides. VCD allied to density functional theory (DFT) calculations allows one to shed some light on the spectral differences of diesters and diamides by studying their conformational properties. Optical rotatory dispersion (ORD) curves confirm the ECD data. Circularly polarized luminescence (CPL) data have been also acquired, which are rather intense in basified solution: the CPL spectra are monosignate and are as intense in the diester and in the diamide case.
authors: Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia , Viale Europa 11, 25123 Brescia, Italy.
authors: Giuseppe
authors: G
authors: Mazzeo
authors: Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia , Viale Europa 11, 25123 Brescia, Italy.|CNISM, Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia , Via della Vasca Navale, 84, 00146 Roma, Italy.
authors: Sergio
authors: S
authors: Abbate
authors: Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia , Viale Europa 11, 25123 Brescia, Italy.|CNISM, Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia , Via della Vasca Navale, 84, 00146 Roma, Italy.
authors: Giovanna
authors: G
authors: Longhi
authors: Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia , Viale Europa 11, 25123 Brescia, Italy.|JASCO Europe , Via Cadorna 1, 23894 Cremella, LC, Italy.
authors: Ettore
authors: E
authors: Castiglioni
authors: Department of Chemistry and Biochemistry, Medical University-Pleven , 1 St. Kl. Ohridski Str., 5800 Pleven, Bulgaria.
authors: Stefan E
authors: SE
authors: Boiadjiev
authors: Department of Chemistry, University of Nevada , Reno, Nevada 89557-0020, United States.
authors: David A
authors: DA
authors: Lightner