Dipole moments and electronic structure of some xanthine and thioxanthine derivatives

Molecular Dynamics Simulation Studies of Caffeine Aggregation in Aqueous Solution

“…For example, in the present case the vacuum dipole moment for caffeine at the MP2/6-311++G** level of theory is 4.55D, while for B3LYP/6-311++G** the vacuum dipole is 3.90D. Experimentally, the reported dipole moment for caffeine in benzene is 3.70(+/- 0.05)D. 40 A starting ESP and Mullikan charge set was calculated and adjusted/scaled to the CHARMM27 all-hydrogen nucleic acid force field. This included adjusting the proton charge at the methyl groups to 0.09 (a standard CHARMM force field requirement).…”

“…For the final charge set (Table 1) the RSMD in the energy difference between the HF/6-31G* and CHARMM results for the seven interaction set was 0.138 kJ/mol, the average difference 0.0374 kJ/mol, and the absolute error 0.0988 kJ/mol, respectively. The final vacuum dipole moment was calculated at 4.3D, which is somewhat higher than the experimentally measured value in benzene (3.7D) 40 but still falls in between the QM vacuum dipole moments of 3.9D for B3LYP/6-311++G** and 4.55D for MP2/6-311++G**. The overall orientation of the dipole moment was maintained.…”

Development of a molecular mechanics force field for caffeine to investigate the interactions of caffeine in different solvent media

“…(In both charge distributions, partial charges on hydrogen atoms were taken as zeros by adding their charges to the connected heavy atom and therefore those zeros were omitted to present a shorter table.) When the dipole moment of caffeine was calculated using these two charge distributions, it was found that both calculated values were not in a good agreement with experimental data [36]. The calculated dipole moments along with the experimental dipole moment are presented in Table 4.…”

Molecular complexes. Part 12.1 Dimeric toluene, torsional vibrations, dipoles and isomeric complexes in 1H NMR studies of weak arene complexes. Temperature dependence of CH signals

“…Second, how can the results in Table 1 indicate a pure 1 : 1 complexation by congruence in K? C and hence also ET have a dipole moment (C: 3.70 debye) 20 and a peripheral complex topology (Fig. 4, left).…”