TY - JOUR

T1 - Intramolecular OHO Hydrogen Bonding in Dibenzoylmethane Enol: Raman Spectroscopic and Quantum Chemical Study

AU - Kolesov, Boris A.

AU - Pritchina, Elena A.

AU - Tikhonov, Aleksey Ya.

N1 - The research was supported by the Ministry of Science and Higher Education of the Russian Federation, N 121031700314-5 and 1021051403061-8-1.4.1 (NIOC SB RAS).

PY - 2023/3

Y1 - 2023/3

N2 - In the present work, the intramolecular O-H···O hydrogen bonding in 3-hydroxy-1,3-diphenylprop-2-en-1-one (keto-enol form of dibenzoylmethane, DBM) was investigated. For this purpose, the Raman spectra of polycrystalline samples of ordinary (H-DBM) and deuterated (D-DBM) 3-hydroxy-1,3-diphenylprop-2-en-1-one in the temperature range of 5–300 K were measured. It was found that low-temperature hydrogen bonding is extremely strong, the proton and deuteron are located in the midpoint of the O···O segment, and their ground and first excited vibrational states are located above the barrier U0 between the local minima. The vibrational frequencies, in this case, are 1543 and 1709 cm−1 for the proton and 1045 and 1087 cm−1 for the deuteron. As the temperature rises and the barrier height increases in H-DBM, the zero-point vibrational state of the proton begins to move into one of the local minima at T > 50 K, while the excited state remains in the broad single-well potential. The same is observed in D-DBM, but with a significant temperature delay. Compounds with donor (−OCH3) and acceptor (−NO2) substituents in the phenyl ring were also synthesized and their spectra were obtained. Both results confirm existing ideas about the nature of the extremely strong hydrogen bond. The quantum-chemical calculation of the vibrational spectrum of H-DBM and D-DBM is consistent with the experimental results.

AB - In the present work, the intramolecular O-H···O hydrogen bonding in 3-hydroxy-1,3-diphenylprop-2-en-1-one (keto-enol form of dibenzoylmethane, DBM) was investigated. For this purpose, the Raman spectra of polycrystalline samples of ordinary (H-DBM) and deuterated (D-DBM) 3-hydroxy-1,3-diphenylprop-2-en-1-one in the temperature range of 5–300 K were measured. It was found that low-temperature hydrogen bonding is extremely strong, the proton and deuteron are located in the midpoint of the O···O segment, and their ground and first excited vibrational states are located above the barrier U0 between the local minima. The vibrational frequencies, in this case, are 1543 and 1709 cm−1 for the proton and 1045 and 1087 cm−1 for the deuteron. As the temperature rises and the barrier height increases in H-DBM, the zero-point vibrational state of the proton begins to move into one of the local minima at T > 50 K, while the excited state remains in the broad single-well potential. The same is observed in D-DBM, but with a significant temperature delay. Compounds with donor (−OCH3) and acceptor (−NO2) substituents in the phenyl ring were also synthesized and their spectra were obtained. Both results confirm existing ideas about the nature of the extremely strong hydrogen bond. The quantum-chemical calculation of the vibrational spectrum of H-DBM and D-DBM is consistent with the experimental results.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85198131389&origin=inward&txGid=79abbfdafbcb894e8a247d43a0499e7d

UR - https://elibrary.ru/item.asp?id=60543022

UR - https://www.mendeley.com/catalogue/e43b7975-c184-3632-a0bc-d06c2e09a324/

U2 - 10.3390/micro3010009

DO - 10.3390/micro3010009

M3 - Article

VL - 3

SP - 107

EP - 117

JO - Micro

JF - Micro

SN - 2673-8023

IS - 1

M1 - 9

ER -