Study of H-bonded cyclic dimer of organic linker 5-Bromoisophthalic acid by DFT and vibrational spectroscopy

• Published in: Journal of molecular structure 2021-10, Vol.1241, p.130613, Article 130613
• Main Authors: P, Ramanna, Tonannavar, Jayashree, Tonannavar, J.
• Format: Article
• Language: English
• Subjects: 5-Bromoisophthalic acid; DFT; H-bonding; Organic linkers; vibrational spectra
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2021.130613

•5-Bromoisophthalic acid is an O O-H•••O bonded dimer verified by IR and Raman modes.•Proposed DFT modeled OO-H•••O bonded cyclic dimer is in agreement with experiment.•Computed 1H NMR δ at ~14 ppm for dimer agrees with reported value of 13.6 ppm.•Electronic structure parameters from NBO, AIM and NCI are calculated and discussed. 5-Bromoisophthalic acid is a potential organic linker in Hydrogen-bonded Organic Frameworks (HOFs). Its H-bonding properties would be determinants, among others, in optimizing the reversible structural transformations, dissolution and re-crystallization, low densities and high porosity. In the present study, a DFT cyclic dimer model computed at B3LYP/cc-pVDZ level based on inter-molecular–OH•••O bonding has been proposed. The proposed cyclic dimer model fits observed vibrational IR and Raman spectral features. Computed chemical shifts for the protons in 5-Bromoisophthalic acid monomer agree with the experimental 1H NMR values in d6-DMSO which dissociates the cyclic dimer into monomers. In the OH (Acceptor) •••O– (Donor) bonding, NBO, AIM and NCI calculations have provided a satisfactory electronic characterization based on orbital overlaps, electron density and associated topological, non-covalent interaction properties consistent with structural and vibrational analysis. [Display omitted]