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Insights on the Auxochromic Properties of the Guanidinium Group
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2016-09-01 00:00:00 , DOI: 10.1021/acs.jpca.6b05180 Ivana Antol 1 , Zoran Glasovac 1 , Davor Margetić 1 , Rachel Crespo-Otero 2 , Mario Barbatti 3
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2016-09-01 00:00:00 , DOI: 10.1021/acs.jpca.6b05180 Ivana Antol 1 , Zoran Glasovac 1 , Davor Margetić 1 , Rachel Crespo-Otero 2 , Mario Barbatti 3
Affiliation
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UV/vis spectra of phenylguanidine (PHGU) in the gas phase and in acetonitrile have been simulated by TD-DFT calculations. Several DFT hybrid and long-range corrected functionals were tested with respect to CASPT2 gas phase calculations. Solvent effects were considered using polarizable continuum model (PCM) and compared with the measured data in acetonitrile. Comparison with isoelectronic phenylurea and related phenyltiourea was done as well. The PBE0 and long-range corrected CAM-B3LYP functionals were selected to investigate the effect of protonation on the excitation energies and absorption intensities of PHGU and several guanidine derivatives with different aromatic chromophoric groups (naphthyl, anthracenyl, quinolinyl, anthraquinonyl, and coumarinyl). Also, the effect of complexation and specific interactions through hydrogen bonds with different anions was examined. It was shown that the protonation of the guanidine subunit shifts the low energy absorption bands toward higher energies (hypsochromic shift). The shift is reduced upon complexation with anions. In phenylguanidine salts, λmax values are correlated to the anion basicity and strength of H-bonding. The observed changes diminish upon increase of chromophoric size (naphthyl, anthracenyl). Theoretical predictions of UV/vis spectra correlate well with experimentally measured spectra of selected guanidine derivatives and their salts.
中文翻译：
胍基团的变色性质的见解
气相和乙腈中苯基胍（PHGU）的UV / vis光谱已通过TD-DFT计算进行了模拟。针对CASPT2气相计算，测试了几种DFT混合动力和远程校正功能。使用可极化连续介质模型（PCM）考虑了溶剂的影响，并将其与乙腈中的测量数据进行了比较。还进行了与等电子苯脲和相关苯基硫脲的比较。选择PBE0和远程校正的CAM-B3LYP官能团，以研究质子化对PHGU和几种具有不同芳香族发色基团（萘基，蒽基，喹啉基，蒽醌和香豆基）的胍衍生物的激发能和吸收强度的影响。还，考察了通过氢键与不同阴离子形成络合物和特定相互作用的影响。结果表明，胍基亚单位的质子化使低能吸收带向高能移动（七色移）。与阴离子络合后，该位移减少。在苯基胍盐中，λ最大值与阴离子碱度和氢键强度相关。观察到的变化随着发色团大小（萘基，蒽基）的增加而减小。UV / vis光谱的理论预测与所选胍衍生物及其盐的实验测量光谱有很好的相关性。
更新日期：2016-09-01
中文翻译：
胍基团的变色性质的见解
气相和乙腈中苯基胍（PHGU）的UV / vis光谱已通过TD-DFT计算进行了模拟。针对CASPT2气相计算，测试了几种DFT混合动力和远程校正功能。使用可极化连续介质模型（PCM）考虑了溶剂的影响，并将其与乙腈中的测量数据进行了比较。还进行了与等电子苯脲和相关苯基硫脲的比较。选择PBE0和远程校正的CAM-B3LYP官能团，以研究质子化对PHGU和几种具有不同芳香族发色基团（萘基，蒽基，喹啉基，蒽醌和香豆基）的胍衍生物的激发能和吸收强度的影响。还，考察了通过氢键与不同阴离子形成络合物和特定相互作用的影响。结果表明，胍基亚单位的质子化使低能吸收带向高能移动（七色移）。与阴离子络合后，该位移减少。在苯基胍盐中，λ最大值与阴离子碱度和氢键强度相关。观察到的变化随着发色团大小（萘基，蒽基）的增加而减小。UV / vis光谱的理论预测与所选胍衍生物及其盐的实验测量光谱有很好的相关性。
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