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Change of Quadrupole Moment upon Excitation and Symmetry Breaking in Multibranched Donor-Acceptor Dyes.
ChemPhysChem ( IF 2.3 ) Pub Date : 2020-07-03 , DOI: 10.1002/cphc.202000253 Zoltán Szakács 1 , Mariusz Tasior 2 , Daniel T Gryko 2 , Eric Vauthey 1
ChemPhysChem ( IF 2.3 ) Pub Date : 2020-07-03 , DOI: 10.1002/cphc.202000253 Zoltán Szakács 1 , Mariusz Tasior 2 , Daniel T Gryko 2 , Eric Vauthey 1
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Upon photoexcitation, a majority of quadrupolar dyes, developed for large two‐photon absorption, undergo excited‐state symmetry breaking (ES‐SB) and behave as dipolar molecules. We investigate how the change of quadrupole moment upon S1←S0 excitation, ΔQ, influences the propensity of a dye to undergo ES‐SB using a series of molecules with a A‐π‐D‐π‐A motif where D is the exceptionally electron‐rich pyrrolo[3,2‐b]pyrrole and A are accepting groups. Tuning of ΔQ is achieved by appending a secondary acceptor group, A’, on both sides of the D core and ES‐SB is monitored using a combination of time‐resolved IR and broadband fluorescence spectroscopy. The results reveal a clear correlation between ΔQ and the tendency to undergo ES‐SB. When A is a stronger acceptor than A’, ES‐SB occurs already in non‐dipolar but quadrupolar solvents. When A and A’ are identical, ES‐SB is only partial even in highly dipolar solvents. When A is a weaker acceptor than A’, the orientation of ΔQ changes, ES‐SB is observed in dipolar solvents only and involves major redistribution of the excitation over the D‐π‐A and D‐A’ branches of the dye.
中文翻译：
多支供体-受体染料在激发和对称性断裂时四极矩的变化。
光激发后，大多数为四光子大吸收而开发的四极染料，经历了激发态对称断裂（ES-SB），并表现为偶极分子。我们研究了S 1 ←S 0激发时四极矩的变化ΔQ如何使用一系列具有A - π - D - π - A基序的分子（其中D为异常富电子的吡咯并[3,2-b]吡咯和A是接受基团。ΔQ的调谐是通过添加次要受体基团A'实现的，使用时间分辨红外和宽带荧光光谱法对D核和ES‐SB的两侧进行监测。结果表明，ΔQ与经历ES‐SB的趋势之间存在明显的相关性。当A是比A'更强的受体时，ES‐SB已经存在于非偶极但四极溶剂中。当A和A'相同时，即使在高度偶极溶剂中，ES‐SB也只是部分。当阿是较弱的受主比A”，的Δ取向Q的变化，ES-SB仅在偶极溶剂观察到，涉及激励的主要再分配在d -染料的π - A和D-A'分支。
更新日期：2020-07-03
中文翻译：
多支供体-受体染料在激发和对称性断裂时四极矩的变化。
光激发后，大多数为四光子大吸收而开发的四极染料，经历了激发态对称断裂（ES-SB），并表现为偶极分子。我们研究了S 1 ←S 0激发时四极矩的变化ΔQ如何使用一系列具有A - π - D - π - A基序的分子（其中D为异常富电子的吡咯并[3,2-b]吡咯和A是接受基团。ΔQ的调谐是通过添加次要受体基团A'实现的，使用时间分辨红外和宽带荧光光谱法对D核和ES‐SB的两侧进行监测。结果表明，ΔQ与经历ES‐SB的趋势之间存在明显的相关性。当A是比A'更强的受体时，ES‐SB已经存在于非偶极但四极溶剂中。当A和A'相同时，即使在高度偶极溶剂中，ES‐SB也只是部分。当阿是较弱的受主比A”，的Δ取向Q的变化，ES-SB仅在偶极溶剂观察到，涉及激励的主要再分配在d -染料的π - A和D-A'分支。
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