Optical Effects of <i>S</i>-Oxidation and M^<i>n</i>+ Binding in <i>meso</i>-Thienyl Dipyrrin Systems and of Stepwise Bromination of 4,4-Difluoro-8-(2,5-dibromo-3-thienyl)-4-bora-3<i>a</i>,4<i>a</i>-diaza-<i>s</i>-indacene

We report 16 novel species and 8 molecular structures in studying how meso-thienyl-substituted dipyrrole oxidation, bromination, and metal ion binding impart optical changes, as monitored by UV−vis absorption/emission spectroscopy. Treatment of 4,4-difluoro-8-(3-benzothienyl)-4-bora-3a,4a-diaza-s-indacene (ϕF = 0.19) with m-CPBA gives selective S-dioxidation (ϕF = 0.006). Results of titrations of transition metal- and “scorpionate”-like dipyrrin species varied under room temperature treatment of m-CPBA. Ni-(thienyl-dipyrrin)n (n = 2) degraded significantly in the presence of m-CPBA, whereas related species (M = Cu, Fe, Co; n = 2, 3) were inert. meso-Thienyl group properties were revealed through the use of 3,4,4-triphenyl-8-(thienyl)-4-bora-3a,4a-diaza-s-indacene; Cu2+ addition resulted in smooth absorption decreases which were modeled to support 1:1 substrate:M2+ binding; for Hg2+ 1:2 substrate:M2+ binding was found. Treatment of 4,4-difluoro-8-(2,5-dibromo-3-thienyl)-4-bora-3a,4a-diaza-s-indacene with Br2 gave red-shifted UV−vis absorption band features that grow with increasing dipyrrin bromination. Structures of the di- and tetra-substituted bromination products were obtained.本研究报道了16种全新物种与8种分子结构，旨在探究中位噻吩取代二吡咯的氧化、溴化反应以及金属离子结合如何引发光学性质变化，相关变化通过紫外-可见吸收/发射光谱法（UV−vis absorption/emission spectroscopy）进行监测。以间氯过氧苯甲酸（m-CPBA）处理4,4-二氟-8-(3-苯并噻吩基)-4-硼-3a,4a-二氮杂-s-引达省（氟化硼二吡咯亚甲基，BODIPY，荧光量子产率ϕF = 0.19），可实现选择性S-双氧化，此时其荧光量子产率降至0.006。过渡金属与类蝎型二吡咯烯（dipyrrin）物种的滴定实验结果显示，室温下经间氯过氧苯甲酸处理后，各物种的反应行为存在显著差异。当n=2时，镍基噻吩取代二吡咯烯配合物在间氯过氧苯甲酸存在下会发生显著降解，而相关金属配合物（M=Cu、Fe、Co；n=2、3）则表现出化学惰性。本研究通过3,4,4-三苯基-8-(噻吩基)-4-硼-3a,4a-二氮杂-s-引达省（氟化硼二吡咯亚甲基，BODIPY）揭示了中位噻吩基团的性质：向体系中加入Cu²+时，吸收强度平稳降低，通过建模分析证实该过程为底物与金属离子以1:1的计量比结合；而加入Hg²+时则观察到底物与金属离子以1:2的计量比结合。以溴素（Br₂）处理4,4-二氟-8-(2,5-二溴-3-噻吩基)-4-硼-3a,4a-二氮杂-s-引达省（氟化硼二吡咯亚甲基，BODIPY）时，其紫外-可见吸收带发生红移，且吸收特征随二吡咯烯的溴代程度提升而逐渐增强，本研究成功解析了二取代与四取代溴代产物的分子结构。