An ab initio study of substituent effects on the excited states of purine derivatives.
Several excited singlet electronic states of purine nucleobases and related derivatives have been calculated using high-level multireference perturbation theory methods. Purine derivatives with one or two amino or carbonyl groups substituted at positions C(2) and/or C(6) of the purine ring have been included in the study. The effect of the substituents on excited-state energies and wave functions is examined. Some trends have been observed, such as the fact that substitution at the C(2) position decreases the energy of the first pi --> pi* state considerably. Although basic qualitative features of the effects can be explained with the simple frontier molecular orbital theory, ab initio calculations are required to describe the effects quantitatively.
Mburu
Elizabeth
E
Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA.
Matsika
Spiridoula
S
D015075:2-Aminopurine / Q000031:analogs & derivatives / Q000737:chemistry; D000225:Adenine / Q000737:chemistry; D004583:Electrons; D005740:Gases / Q000737:chemistry; D006147:Guanine / Q000737:chemistry; D019271:Hypoxanthine / Q000737:chemistry; D007536:Isomerism; D011687:Purines / Q000737:chemistry*; D011789:Quantum Theory; D019820:Xanthine / Q000737:chemistry
D005740:Gases; D011687:Purines; D019820:Xanthine; D019271:Hypoxanthine; D015075:2-Aminopurine; C007300:2,6-diaminopurine; D006147:Guanine; C008183:isoguanine; D000225:Adenine; C030985:purine