Adenine conical intersections

Figure 11-8. Structures of representative conical intersections Sj/Sq in the purine bases, 9H-adenine and 9H-guanine. Adenine structures (a,b) are taken from Ref. [138]. Guanine structure (c) is taken from Ref. [171]...

Figure 11-9. CASSCF potential-energy profiles of the ground-state So (circles), the lnjr state (triangles), the Lb state (squares), and the La state (filled squares) of the 9H-adenine along the linear interpolation reaction path from the equilibrium geometry of the nit state to the CI32 (a) and CI16 (b) conical intersections. The diabatic correlation of the states is shown in (a). (From Ref. [138])...

Figure 11-16. Diagram of the energy levels at the two- and three-state conical intersections in uracil and adenine calculated at the MRCI level, ciIJK represents conical intersection between states Sj, S j, S -. (From Ref. [210])...

Nielsen SB, Soiling TI (2005) Are conical intersections responsible for the ultrafast processes of adenine, protonated adenine, and the corresponding nucleosides . Chem Phys Chem 6 1276... 

Yamazaki S, Kato S (2007) Solvent effect on conical intersections in excited-state 9H-adenine radiationless decay mechanism in polar solvent. J Am Chem Soc 129 2901—2909... 

Table 8-1. S, energy and Cremer-Pople parameters for the ring puckering conical intersections in aminopyrimidine, pyridone and pyrrole. Energies relative to the S0 energy in the ground state equilibrium geometry. The values in parenthesis are the CP parameters for the equivalent MXSs in 9H-adenine using the geometries given in [5]...

Figure 16-4. Scheme proposed, based on CASPT2 calculations, for the main decay pathways of adenine (A), measured in molecular beams with intrinsic lifetimes t, < 100 fs and t2 1 ps. Energies in kcal mol-1 referred to the lowest conical intersection. A similar scheme is proposed for guanine (G). (Reproduced from Ref. [50] with permission from Wiley-VCH Verlag)... 

Fig. 6 Basics of the theoretical model for charge transport based on conical intersections (Coins) and the excimer-Hke interaction between the donor and acceptor electronic states of a molecular system formed by 2 monomers (a), PESs of the donor and acceptor electronic states in the adenine-cytosine (AC) heterodimer and the cytosine-cytosine homodimer (b) and scheme of the Coin-based mechanism for charge transport in DNA (c).

The existence of a conical intersection of the lowest n-a state with the ground state is a general property of planar aromatic systems containing hydroxy or azine groups. The H-detachment intersection has been documented along the N-H stretch coordinate in (c) pyrrole, and (d) 9H tautomer of adenine (Fig. 19). ° A similar conical intersection mediating 0-H cleavage has been identified in phenol [Fig. 19(e)]. 

Figure 6 Energy levels at the two- and three-state conical intersection points using MRCI, (a) the So, Si, Si states of uracil and (b) the So, Si, Si, S3, S4 states of adenine. Rx(ciIJ) and Rx(ciIJK) denote conical intetsection between states /,/ ot I,J,K, tespectively. Reproduced with petmission from Ref. 94.

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