Atilgan Ahmet, Beldjoudi Yassine, Yu Jierui, Kirlikovali Kent O, Weber Jacob A, Liu Jian, Jung Dahee, Deria Pravas, Islamoglu Timur, Stoddart J Fraser, Farha Omar K, Hupp Joseph T
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
Department of Chemistry and Biochemistry, Southern Illinois University, 1245 Lincoln Drive, Carbondale, Illinois 62901, United States.
ACS Appl Mater Interfaces. 2022 Mar 16;14(10):12596-12605. doi: 10.1021/acsami.1c21750. Epub 2022 Mar 2.
Effective heterogeneous photocatalysts capable of detoxifying chemical threats in practical settings must exhibit outstanding device integrity. We report a copolymerization that yields robust, porous, processible, chromophoric BODIPY (BDP; boron-dipyrromethene)-containing polymers of intrinsic microporosity (BDP-PIMs). Installation of a pentafluorophenyl at the meso position of a BDP produced reactive monomer that when combined with 5,5,6,6-tetrahydroxy-3,3,3,3-tetramethyl-1,1-spirobisindane (TTSBI) and tetrafluoroterephthalonitrile (TFTPN) yields . Postsynthetic modification of these polymers yields and ─polymers containing bromine at the 2,6-positions. Remarkably, the brominated polymers display porosity and processability features similar to those of H-BDP-PIMs. Gas adsorption reveals molecular-scale porosity and Brunette-Emmet-Teller surface areas as high as 680 m g. Electronic absorption spectra reveal charge-transfer (CT) bands centered at 660 nm, while bands arising from local excitations, LE, of BDP and TFTPN units are at 530 and 430 nm, respectively. Fluorescence spectra of the polymers reveal a Förster resonance energy-transfer (FRET) pathway to BDP units when TFTPN units are excited at 430 nm; weak phosphorescence at room temperature indicates a singlet-to-triplet intersystem crossing. The low-lying triplet state is well positioned energetically to sensitize the conversion of ground-state (triplet) molecular oxygen to electronically excited singlet oxygen. Photosensitization capabilities of these polymers toward singlet-oxygen-driven detoxification of a sulfur-mustard simulant 2-chloroethyl ethyl sulfide (CEES) have been examined. While excitation of CT and LE bands yields weak catalytic activity ( > 15 min), excitation to higher energy states of TFTPN induces significant increases in photoactivity ( ≅ 5 min). The increase is attributable to (i) enhanced light collection, (ii) FRET between TFTPN and BDP, (iii) the presence of heavy atoms (bromine) having large spin-orbit coupling energies that can facilitate intersystem crossing from donor-acceptor CT-, FRET-, or LE-generated BDP singlet states to BDP-related triplet states, and (iv) polymer triplet excited-state sensitization of the formation of CEES-reactive, singlet oxygen.
能够在实际环境中对化学威胁进行解毒的高效非均相光催化剂必须具备出色的器件完整性。我们报道了一种共聚反应，该反应可生成具有坚固性、多孔性、可加工性且含有发色团硼二吡咯亚甲基（BDP）的固有微孔聚合物（BDP-PIMs）。在BDP的中位位置引入五氟苯基可生成反应性单体，该单体与5,5,6,6-四羟基-3,3,3,3-四甲基-1,1-螺双茚满（TTSBI）和四氟对苯二甲腈（TFTPN）结合后可生成……。对这些聚合物进行后合成修饰可生成……以及在2,6位含有溴的聚合物。值得注意的是，溴化聚合物表现出与H-BDP-PIMs类似的孔隙率和可加工性特征。气体吸附显示出分子尺度的孔隙率和高达680 m²/g的布鲁诺尔-埃米特-泰勒表面积。电子吸收光谱显示以660 nm为中心的电荷转移（CT）带，而BDP和TFTPN单元的局部激发（LE）产生的带分别位于530和430 nm处。聚合物的荧光光谱显示，当TFTPN单元在430 nm处被激发时，存在一条向BDP单元的Förster共振能量转移（FRET）途径；室温下的弱磷光表明存在单重态到三重态的系间窜越。低位三重态在能量上处于有利位置，可敏化基态（三重态）分子氧向电子激发单重态氧的转化。已研究了这些聚合物对单重态氧驱动的硫芥模拟物2-氯乙基乙基硫醚（CEES）解毒的光敏化能力。虽然CT和LE带的激发产生较弱的催化活性（>15分钟），但将TFTPN激发到更高能量状态会导致光活性显著增加（≅5分钟）。这种增加归因于：（i）光收集增强；（ii）TFTPN和BDP之间的FRET；（iii）存在具有大自旋-轨道耦合能的重原子（溴），其可促进从供体-受体CT、FRET或LE产生的BDP单重态到BDP相关三重态的系间窜越；（iv）聚合物三重态激发态对CEES反应性单重态氧形成的敏化作用。
