Photoluminescence of Seven-Coordinate Zirconium and Hafnium Complexes with 2,2′-Pyridylpyrrolide Ligands

Luminescent seven-coordinated zirconium and hafnium complexes bearing three mono-anionic 2,2′-pyridylpyrrolide ligands and one chloride were synthesized. Solid-state structures and the dynamic behaviors in solution were probed by X-ray crystallography and variable temperature ¹H NMR experiments, respectively. Absorption spectroscopy and time-dependent density functional theory (TD-DFT) calculations supported a hybrid of ligand-to-metal charge transfer (LMCT)/ligand-to-ligand charge transfer (LLCT) for the visible light absorption band. The complexes (^MePMP^Me)₃MCl (M=Zr, Hf, ^MePMP^Me=3,5-dimethyl-2-(2-pyridyl)pyrrolide) are emissive in solution at room temperature upon irradiation with visible light due to a combination of phosphorescence and fluorescence characterized by excited state lifetimes in the μs and low to sub-ns timescale, respectively. Electrochemical experiments revealed that the zirconium complex possesses a reversible redox event under highly reducing condition (−2.29 V vs. Fc^+/0).     

Hitherto-Unexplored Photodynamic Therapy of Ag2S and Enhanced Regulation Based on Polydopamine In Vitro and Vivo

Given their superior penetration depths, photosensitizers with longer absorption wavelengths present broader application prospects in photodynamic therapy (PDT). Herein, Ag₂S quantum dots were discovered, for the first time, to be capable of killing tumor cells through the photodynamic route by near-infrared light irradiation, which means relatively less excitation of the probe compared with traditional photosensitizers absorbing short wavelengths. On modification with polydopamine (PDA), PDA-Ag₂S was obtained, which showed outstanding capacity for inducing reactive oxygen species (increased by 1.69 times). With the addition of PDA, Ag₂S had more opportunities to react with surrounding O₂, which was demonstrated by typical triplet electron spin resonance (ESR) analysis. Furthermore, the PDT effects of Ag₂S and PDA-Ag₂S achieved at longer wavelengths were almost identical to the effects produced at 660 nm, which was proved by studies in vitro. PDA-Ag₂S showed distinctly better therapeutic effects than Ag₂S in experiments in vivo, which further validated the enhanced regulatory effect of PDA. Altogether, a new photosensitizer with longer absorption wavelength was developed by using the hitherto-unexplored photodynamic function of Ag₂S quantum dots, which extended and enhanced the regulatory effect originating from PDA.     

Covalently Assembled Dipeptide Nanospheres as Intrinsic Photosensitizers for Efficient Photodynamic Therapy in Vitro

Monodispersed diphenylalanine‐based nanospheres with excellent biocompatibility are fabricated through a facile covalent reaction‐induced assembly. Interestingly, the nanospheres exhibit red autofluorescence. Most importantly, such assembled dipeptide nanospheres can serve as intrinsic photosensitizer to convert O₂ to singlet oxygen (¹O₂). Thus, photodynamic therapy in vitro can be achieved effectively. The versatile strategy could be extended to other biomolecules containing a primary amine group for the fabrication of potential intrinsic photosensitizers.     

化学增感对苯并三氮唑银的PTG材料感光性能的影响

本文主要研究了传统卤化银照相材料中的增感技术,如硫增感、金增感、硫加金协同增感,对新型的以苯并三氮唑银为银源、水性聚乙烯醇为粘合剂的光敏热成像材料增感是否有效的问题。结果显示,传统化学增感对异位法制备的溴化银为光敏剂的光敏热成像材料具有很好的增感效果,硫加金协同增感的效果要好于单独的硫增感和金增感;传统化学增感对原位法制备的溴化银为光敏剂的光敏热成像材料没有增感效果,反而减感,硫加金减感效果最严重。     

Broadband Visible Light-Absorbing [70]Fullerene-BODIPY-Triphenylamine Triad: Synthesis and Application as Heavy Atom-Free Organic Triplet Photosensitizer for Photooxidation

A broadband visible light-absorbing [70]fullerene-BODIPY-triphenylamine triad (C₇₀-B-T) has been synthesized and applied as a heavy atom-free organic triplet photosensitizer for photooxidation. By attaching two triphenylmethyl amine units (TPAs) to the π-core of BODIPY via ethynyl linkers, the absorption range of the antenna is extended to 700 nm with a peak at 600 nm. Thus, the absorption spectrum of C₇₀-B-T almost covers the entire UV–visible region (270–700 nm). The photophysical processes are investigated by means of steady-state and transient spectroscopies. Upon photoexcitation at 339 nm, an efficient energy transfer (ET) from TPA to BODIPY occurs both in C₇₀-B-T and B-T, resulting in the appearance of the BODIPY emission at 664 nm. Direct or indirect (via ET) excitation of the BODIPY-part of C₇₀-B-T is followed by photoinduced ET from the antenna to C₇₀, thus the singlet excited state of C₇₀ (¹C₇₀^*) is populated. Subsequently, the triplet excited state of C₇₀ (³C₇₀^*) is produced via the intrinsic intersystem crossing of C₇₀. The photooxidation ability of C₇₀-B-T was studied using 1,5-dihydroxy naphthalene (DHN) as a chemical sensor. The photooxidation efficiency of C₇₀-B-T is higher than that of the individual components of C₇₀-1 and B-T, and even higher than that of methylene blue (MB). The photooxidation rate constant of C₇₀-B-T is 1.47 and 1.51 times as that of C₇₀-1 and MB, respectively. The results indicate that the C₇₀-antenna systems can be used as another structure motif for a heavy atom-free organic triplet photosensitizer.     

溶酶体靶向吲哚氟硼二吡咯光敏剂的合成、 双光子荧光成像及光动力治疗

通过Knoevenagel缩合反应制备了一个具有溶酶体靶向的近红外光敏剂IMBDP-Lys, 用于双光子荧光成像和光动力治疗. IMBDP-Lys由2个吲哚吗啉功能团连接到氟硼二吡咯(BODIPY)母核的3?位和8?位构筑而成, 是一种重原子诱导的光敏剂. 采用高斯09W理论计算光敏剂S₁态和T₂态能量值相差0.12 eV, 可以有效地发生系间窜越. 在二氯甲烷溶液中, 光敏剂IMBDP-Lys的最大吸收波长为631 nm, 最大发射波长为684 nm. 在 660 nm的光照下, 以亚甲基蓝为参比, 单线态氧量子产率经计算为48.3%. 此外, 含有2个吗啉基团的光敏剂IMBDP-Lys具有良好的生物相容性和精准的靶向能力, 可以快速地进入斑马鱼体内进行双光子荧光成像, 并且与溶酶体绿色染料Lyso-Tracker Green共定位系数为0.95. 溴化噻唑蓝四氮唑(MTT)实验结果表明, 光敏剂具有低的暗毒性(≥85%)和高的光毒性(IC₅₀=0.52 μmol/L). 在660 nm的光照下, 利用活性氧荧光探针2’,7’-二氯二氢荧光素二乙酸酯（DCFH-DA）证明光敏剂可以产生活性氧, 同时吖啶橙/溴化乙锭(AO/EB)染色实验和细胞迁移实验表明产生的活性氧不仅能诱导A549细胞凋亡, 还能有效地抑制肿瘤细胞迁移. 因此, 近红外光敏剂IMBDP-Lys在双光子荧光成像和溶酶体靶向的光动力治疗中具有重要的应用价值.     

Pyrimidoquinazolinophenanthroline Opens Next Chapter in Design of Bridging Ligands for Artificial Photosynthesis**

The synthesis and detailed characterization of a new Ru polypyridine complex containing a heteroditopic bridging ligand with previously unexplored metal-metal distances is presented. Due to the twisted geometry of the novel ligand, the resultant division of the ligand in two distinct subunits leads to steady state as well as excited state properties of the corresponding mononuclear Ru(II) polypyridine complex resembling those of prototype [Ru(bpy)₃]²⁺ (bpy=2,2'-bipyridine). The localization of the initially optically excited and the nature of the long-lived excited states on the Ru-facing ligand spheres is evaluated by resonance Raman and fs-TA spectroscopy, respectively, and supported by DFT and TDDFT calculations. Coordination of a second metal (Zn or Rh) to the available bis-pyrimidyl-like coordination sphere strongly influences the frontier orbitals, apparent by, for example, luminescence quenching. Thus, the new bridging ligand motif offers electronic properties, which can be adjusted by the nature of the second metal center. Using the heterodinuclear Ru−Rh complex, visible light-driven reduction of NAD⁺ to NADH was achieved, highlighting the potential of this system for photocatalytic applications.     

Synthesis of Cationic Dumbbell-shaped Fullerene Nanostructures as Potential Photodynamic Sensitizers

A design of novel hydrophilic tetracationic dumbbell-shaped [60]fullerene nanostructures was made by balancing the hydrophilicity and hydrophobicity characteristics of the fullerene adduct for their potential application as photodynamic sensitizers in the PDT treatment. A sequential protection-deprotection reaction pathway was applied for the functional differentiation between primary and secondary amine moieties of pentaethylene hexamine. Synthesis of the target molecule involves two key steps of unsymmetrical esterification and amidation of malonic acid and subsequent fullerenation. The synthetic strategy was accomplished using mild reaction conditions in the intermediate molecule preparation and led a moderate overall product yield.     

Selective Photocatalytic Oxidation of Sulfides in Lanthanide Metal -Organic Frameworks Incorporating Ru(2,2′-bpy)3 photosensitizer

Three isostructural lanthanide metal-organic frameworks (Ln-MOFs) were synthesized with uncoordinated N^N site, and the Ru(N^N)₃ photosensitizer was introduced via coordination link. These functionalized frameworks showed excellent performance in the photocatalytic oxidation of sulfides with good conversion and high sulfoxide selectivity.     

Polymerization kinetics of phosphonic acids and esters using an iodonium initiator

Phosphonic acids are known to be useful monomers in dental restorative materials because of their good potential to provide enhanced adhesion to hydroxyapatite and their high hydrolytic stability. In this study, the photopolymerization of phosphonic acid‐based monomer via the camphorquinone (CQ)/ethyl‐4‐(dimethylaminobenzoate) (EDAB) photoredox system is compared with a ternary system composed of iodonium hexafluorophosphate and CQ/EDAB. Photocalorimetry shows that the ternary system does not provide a significant acceleration of the polymerization with either acrylamide or methacrylate phosphonic acids. The complexation of the iodonium by the phosphonic moiety of the acidic monomers leads to a lowered iodonium reactivity and reduced polarizability of the medium and as a consequence limits the rate enhancement effect normally observed by phosphonic acids on the polymerization rate. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5046–5055