Determination of the structure of 1,1 '-diethyl-2,2 '-carbocyanine iodide using NMR spectra and GIAO-HF/DFT calculations

作者：Kim Se Mi; Kim Dong Hee^*

来源：Dyes and Pigments, 2008, 79(1): 1-6.

DOI：10.1016/j.dyepig.2007.12.008

• carbocyanine
• PCYN
• NMR spectroscopy
• PES
• GIAO-HF/DFT
• molecular structure

The chemical shift assignments of pinacyanol (1,1-diethyl-2,2'-carbocyanine) iodide were obtained by means of 1-D ((1)H and (13)C) and 2-D ((1)H-(1)H COSY, (13)C-(1)H COSY, and HMBC) NMR and theoretical calculations (GIAO-HF and GIAO-DFT using the 6-31 +G(d,p) basis set). An optimized structure, calculated using B3LYP/6-31G(d), of the stable conformer gave a twist angle of gamma = 23.4 degrees between the pairs of the quinoline planes, which was 0.4 kcal/mol lower than when gamma = 0 degrees. The (2E, 12E) conformer having C(2) symmetry, matched well with the calculated and experimental (13)C and (1)H NMR chemical shifts in DMSO-d(6); GIAO-DFT provided better correlation (R(2) = 0.997, (13)C; R(2) = 0.978, (1)H) than GIAO-HF (R(2) = 0.968, (13)C; R(2) = 0.949, (1)H).

• 出版日期2008-10