Abstract

A comprehensive Raman spectroscopic/electronic structure study of hydrogen bonding by pyrimidine with eight different polar solvents is presented. Raman spectra of binary mixtures of pyrimidine with methanol and ethylene glycol are reported, and shifts in ν1, ν3, ν6a, ν6b, ν8a, ν8b, ν9a, ν15, ν16a, and ν16b are compared to earlier results obtained for water. Large shifts to higher vibrational energy, often referred to as blue shifts, are observed for ν1, ν6b, and ν8b (by as much as 14 cm-1). While gradual blue shifts with increasing hydrogen bond donor concentration are observed for ν6b and ν8b, ν1 exhibits three distinct spectral components whose relative intensities vary with concentration. The blue shift of ν1 is further examined in binary mixtures of pyrimidine with acetic acid, thioglycol, phenyl methanol, hexylamine, and acetonitrile. Electronic structure computations for more than 100 micro solvated structures reveal a significant dependence of the magnitude of the ν1 blue shift on the local micro solvation geometry. Results from natural bond orbital (NBO) calculations also reveal a strong correlation between charge transfer and blue shifting of pyrimidine's normal modes. Although charge transfer has previously been linked to blue shifting of the X-H stretching frequency in hydrogen bond donors, here, a similar trend in a hydrogen bond acceptor is demonstrated. © 2013 American Chemical Society.

Department(s)

Chemistry

Publication Status

Open Access

Comments

National Science Foundation, Grant 0955550

International Standard Serial Number (ISSN)

1520-5215; 1089-5639

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Chemical Society, All rights reserved.

Publication Date

03 Jul 2013

PubMed ID

23679020

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