MODIFICATION OF SPIN-DENSITY DISTRIBUTION VIA SPECIFIC HYDROGEN-BOND INTERACTIONS - AN EXPERIMENTAL, UHF, AND DENSITY-FUNCTIONAL STUDY

A combined experimental/computational study has been carried out on th e effect of hydrogen bond complex formation between the radical anion of naphthalimide and the acylated diaminopyridine receptor 2. Experime ntal hyperfine coupling constants (hfc's) were obtained via simultaneo us electrochemistry and EPR (SEEPR). An overall increase in the absolu te values of the hfc's is observed. To better correlate experimental r esults with changes in electronic structure, hfc's were calculated usi ng UHF and UKS wave functions, specifically the B3LYP hybrid functiona l. While the UHF derived hfc's reproduce qualitative trends, the hfc's obtained by density functional calculations are in good quantitative agreement with the experimental data. B3LYP calculations show an incre ase in spin polarization, with the largest effect observed in the naph thyl moiety, consistent with experimental results.