Recent advances in visible light photocatalysis represent a significant stride towards sustainable catalytic chemistry. However, its successful implementation in fine chemical production remains challenging and requires careful optimization of available photocatalysts. Our work aims to structurally modify bioinspired porphyrin catalysts, addressing issues related to their laborious synthesis and low solubility, with the goal of increasing their efficiency and developing reusable catalytic systems. We have demonstrated the catalytic potential of readily available meso-tetrakis[4-(diethoxyphosphoryl)phenyl]porphyrins (M(TPPP)). Novel metal (Pd(II), Co(II) and In(III)) complexes with this ligand were prepared in good yields. These chromophores were characterized in solution using spectroscopic (NMR, UV–vis, fluorescence) and electrochemical methods. The introduction of phosphonate groups on the phenyl substituents of meso-tetraphenylporphyrins (M(TPP)) improves solubility in polar organic solvents without significantly altering the photophysical properties and photostability of complexes. This structural modification also leads to easier reductions and harder oxidations of the macrocycle for all investigated complexes compared to the corresponding TPP derivatives. The free base porphyrin, zinc(II), palladium(II), and indium(III) complexes were studied as photocatalysts for oxidation of sulfides to sulfoxides using molecular oxygen as a terminal oxidant. Both dialkyl and alkyl aryl sulfides were quantitatively transformed into sulfoxides under blue LED irradiation in the acetonitrile–water mixture (10 : 1 v/v) with a low loading (0.005–0.05 mol%) of porphyrin photocatalysts, where H₂(TPPP) and Pd(TPPP) were found to be the most efficient. The reaction mechanism was studied using photoluminescence and EPR spectroscopies. Then, to access reusable catalysts, water-soluble derivatives bearing phosphonic acid groups, H₂(TPPP-A) and Pd(TPPP-A), were prepared in high yields. These compounds were characterized using spectroscopic methods. Single-crystal X-ray diffraction analysis of Pd(TPPP-A) reveals that the complex forms a 3D hydrogen-bonded organic framework (HOF) in the solid state. Both H₂(TPPP-A) and Pd(TPPP-A) were found to catalyze the photooxidation of sulfides by molecular oxygen in the acetonitrile–water mixture (1 : 1 v/v), while only Pd(TPPP-A) resulted in selective production of sulfoxides. The complex Pd(TPPP-A) was easily recovered through extraction in the aqueous phase and successfully reused in five consecutive cycles of the sulfoxidation reaction.

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膦酸酯取代的卟啉作为高效、经济且可重复使用的光催化剂

可见光光催化的最新进展代表了可持续催化化学的重大进步。然而，其在精细化学品生产中的成功实施仍然具有挑战性，需要仔细优化可用的光催化剂。我们的工作旨在对仿生卟啉催化剂进行结构修饰，解决其合成繁琐和溶解度低的问题，以提高其效率并开发可重复使用的催化系统。我们已经证明了容易获得的内消旋四[4-(二乙氧基磷酰基)苯基]卟啉(M(TPPP))的催化潜力。与该配体的新型金属（Pd（II），Co（II）和In（III））配合物以良好的产率制备。使用光谱（NMR、紫外-可见光、荧光）和电化学方法在溶液中对这些发色团进行表征。在内消旋四苯基卟啉（M（TPP））的苯基取代基上引入膦酸酯基团可提高在极性有机溶剂中的溶解度，而不会显着改变配合物的光物理性质和光稳定性。与相应的 TPP 衍生物相比，这种结构修饰还导致所有研究的配合物的大环更容易还原和更难氧化。研究了游离碱卟啉、锌( II )、钯( II )和铟( III )配合物作为光催化剂，使用分子氧作为末端氧化剂将硫化物氧化成亚砜。在乙腈-水混合物（10:1 v/v）中，在低负载量（0.005-0.05 mol%）卟啉光催化剂中，二烷基硫醚和烷基芳基硫醚在蓝色 LED 照射下定量转化为亚砜，其中 H ₂ (TPPP)发现 Pd(TPPP) 是最有效的。利用光致发光和 EPR 光谱研究了反应机理。然后，为了获得可重复使用的催化剂，以高产率制备了带有膦酸基团的水溶性衍生物H ₂ (TPPP-A)和Pd(TPPP-A)。使用光谱方法对这些化合物进行了表征。 Pd(TPPP-A) 的单晶 X 射线衍射分析表明，该配合物在固态下形成 3D 氢键有机骨架 (HOF)。发现H ₂ (TPPP-A) 和Pd(TPPP-A) 都能催化乙腈-水混合物(1 : 1 v/v) 中分子氧对硫化物的光氧化反应，而只有Pd(TPPP-A) 产生光氧化反应。选择性生产亚砜。通过在水相中萃取，可以轻松回收络合物 Pd(TPPP-A)，并在连续五个磺化反应循环中成功重复使用。