Spectroscopic investigations and hydrogen bond interactions of 8-aza analogues of xanthine, theophylline and caffeine: a theoretical study

Karthika, M.; Kanakaraju, R.; Lakshmipathi, Senthilkumar

doi:10.1007/s00894-012-1742-3

Cited by 9 publications

(4 citation statements)

References 43 publications

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“…The relative energies, rotational constants, dipole moments and harmonic frequencies of the two most stable tautomers remain for future experimental 8 verification. The structure and spectroscopic properties of theophylline and its analogous molecules 44,45 can be compared to our results.…”

Section: Optimized Geometries Of Theophylline Monomer and Its Hydratementioning

confidence: 86%

Spectroscopic signatures and structural motifs in isolated and hydrated theophylline: a computational study

Singh

2015

RSC Adv.

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The spectra and structures of theophylline monomer and dimer and their hydrated complex have been investigated by MP2 and DFT methods. The ground state geometry optimization yield five lowest energy conformers of Tph 1 -(H 2 O) 1 complex at the M06-2X/6-311++G(d,p) level of theory for the first time. We investigated the low-lying excited states of bare theophylline by means of coupled cluster singles and approximate doubles (CC2) and TDDFT methods and a satisfactory interpretation of the electronic absorption spectra (Phys. Chem. Chem. Phys., 2012,14,10677-10682) is obtained. One striking feature is the coexistence of the blue and red shift of the vertical excitation energy of the optically bright state S 1 ( 1 ππ* ) of theophylline upon forming complex with a water at C 2 =O and C 6 =O carbonyl sites, respectively. The optimized structure of newly characterized theophylline dimer Form IV,computed the first time by MP2 and DFT methods. The binding energy of this dimer linked by double N-H…O=C hydrogen bonds was found to be 88 kj/mole at the MP2/6-311++G(d,p) level of theory. The geometry optimization of dimer Form M has also been performed and found that further stability is being conferred to the dimer IV after hydration. Computed IR spectra is found in remarkable agreement with the experiment (Cryst. Growth Des. 2010, 10, 3879-3886) and the out of phase (C=O) 2 stretching mode shows tripling of intensity upon dimerisation. The vertical excitation energy of the optically bright state S 1 ( 1 ππ* ) of theophylline monomer upon forming dimer IV is shifted towards red as well as blue.

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Section: Optimized Geometries Of Theophylline Monomer and Its Hydratementioning

confidence: 86%

Spectroscopic signatures and structural motifs in isolated and hydrated theophylline: a computational study

Singh

2015

RSC Adv.

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“…Structural information, such as distances, relative orientations, or changes in environmental conditions, can be obtained from FRET, LD, and CD once the spectroscopic results can be put into the appropriate context of the corresponding active transition moments. − Accurate information about the directions of the transition moments and the purity of polarization (i.e., overlap between differently polarized transitions) are then particularly important to have. In addition, advances in quantum mechanical (QM) computation have made theoretical approaches very useful in the molecular understanding of the effects the surrounding environment may have on electronic properties of a given chromophore. ,− …”

Section: Introductionmentioning

confidence: 99%

UV Transition Moments of Tyrosine

et al. 2014

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To assist polarized-light spectroscopy for protein-structure analysis, the UV spectrum of p-cresol, the chromophore of tyrosine, was studied with respect to transition moment directions and perturbation by solvent environment. From linear dichroism (LD) spectra of p-cresol aligned in stretched matrices of poly(vinyl alcohol) and polyethylene, the lowest π-π* transition (Lb) is found to have pure polarization over its entire absorption (250-300 nm) with a transition moment perpendicular to the symmetry axis (C1-C4), both in polar and nonpolar environments. For the second transition (La), polarized parallel with the symmetry axis, a certain admixture of intensity with orthogonal polarization is noticed, depending on the environment. While the Lb spectrum in cyclohexane shows a pronounced vibrational structure, it is blurred in methanol, which can be modeled as due to many microscopic polar environments. With the use of quantum mechanical (QM) calculations, the transition moments and solvent effects were analyzed with the B3LYP and ωB97X-D functionals in cyclohexane, water, and methanol using a combination of implicit and explicit solvent models. The blurred Lb band is explained by solvent hydrogen bonds, where both accepting and donating a hydrogen causes energy shifts. The inhomogeneous solvent-shift sensitivity in combination with robust polarization can be exploited for analyzing tyrosine orientation distributions in protein complexes using LD spectroscopy.

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“…The absorption intensity is directly related to the dimensionless oscillator strength, and the dominant absorption bands are the transitions with the highest oscillator strength value [33]. For conformer Esp, the dominant absorption cor-responds to the H-3→L transition.…”

Section: Absorption Propertiesmentioning

confidence: 99%

Stability and Reactivity of Two Benzimidazole Hydrazide-Hydrazone Compounds: A Theoretical Study by DFT Method

Assoma,

Bede,

Achi

et al. 2024

IJCTC

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This work contributes to theoretical chemistry’s knowledge of benzimidazole-hydrazide-hydrazone. Indeed, hydrazides-hydrazones-benzimidazoles have shown anticancer, antibacterial, antiparasitic activities, and many other activities. A benzimidazole-hydrazide-hydrazone compound can exhibit four conformers: E/Z synperiplanar (Esp, Zsp) and E/Z antiperiplanar (Eap, Zap). Studies have indicated that the prevalence of these compounds is attributed to their stability and their tendency to readily bind to DNA. A theoretical study with advanced methods would make it possible to evaluate the stability of benzimidazole-hydrazide-hydrazone conformers. Therefore, we carried out this theoretical study on the conformers of two benzimidazoles-hydrazides-hydrazones denoted C1 and C2 wich differ by the presence of fluorine atom in the structure of C2. Specifically, we analyze the stability and the reactivity of the compounds based on the dipole moment, Gibbs free energy, HOMO and LUMO energies and UV-visible. For this purpose, calculations were performed in gas phase and DMSO using DFT and TD-DFT methods at the B3LYP/6-311+G(d, p) level theory. The dipole moment values show that Zap conformer is the most polar for both compounds. The Gibbs free energy indicate that Esp conformer emerges as the most stable for both compounds in both phases. The energy gap (ELUMO-EHOMO) and TD-DFT results suggest that Esp conformer is the most reactive conformer for the two compounds.

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Spectroscopic investigations and hydrogen bond interactions of 8-aza analogues of xanthine, theophylline and caffeine: a theoretical study

Cited by 9 publications

References 43 publications

Spectroscopic signatures and structural motifs in isolated and hydrated theophylline: a computational study

Spectroscopic signatures and structural motifs in isolated and hydrated theophylline: a computational study

UV Transition Moments of Tyrosine

Stability and Reactivity of Two Benzimidazole Hydrazide-Hydrazone Compounds: A Theoretical Study by DFT Method

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