Fedotov, Daniil A.; Paul, Alexander C.; Koch, Henrik; Santoro, Fabrizio; Coriani, Sonia; Improta, Roberto published an article in 2022, the title of the article was Excited state absorption of DNA bases in the gas phase and in chloroform solution: a comparative quantum mechanical study.Product Details of 65-71-4 And the article contains the following content:
We study the excited state absorption (ESA) properties of the four DNA bases (thymine, cytosine, adenine, and guanine) by different single reference quantum mech. methods, namely, equation of motion coupled cluster singles and doubles (EOM-CCSD), singles, doubles and perturbative triples (EOM-CC3), and time-dependent d. functional theory (TD-DFT), with the long-range corrected CAM-B3LYP functional. Preliminary results at the Tamm-Dancoff (TDA) CAM-B3LYP level using the maximum overlap method (MOM) are reported for thymine. In the gas phase, the three methods predict similar One Photon Absorption (OPA) spectra, which are consistent with the exptl. results and with the most accurate computational studies available in the literature. The ESA spectra are then computed for the ππ* states (one for pyrimidine, two for purines) associated with the lowest-energy absorption band, and for the close-lying nπ* state. The EOM-CC3, EOM-CCSD and CAM-B3LYP methods provide similar ESA spectral patterns, which are also in qual. agreement with literature RASPT2 results. Once validated in the gas phase, TD-CAM-B3LYP has been used to compute the ESA in chloroform, including solvent effects by the polarizable continuum model (PCM). The predicted OPA and ESA spectra in chloroform are very similar to those in the gas phase, most of the bands shifting by less than 0.1 eV, with a small increase of the intensities and a moderate destabilization of the nπ* state. Finally, ESA spectra have been computed from the min. of the lowest energy ππ* state, and found in line with the available exptl. transient absorption spectra of the nucleosides in solution, providing further validation of our computational approach. The experimental process involved the reaction of 5-Methylpyrimidine-2,4(1H,3H)-dione(cas: 65-71-4).Product Details of 65-71-4
The Article related to thymine cytosine nucleobase excited state absorption transient spectra, Physical Organic Chemistry: Other Reactions, Processes, and Spectra and other aspects.Product Details of 65-71-4
Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia