可见光诱导下磺酰氯参与的C-磺酰基化合物的合成研究进展

C-磺酰基化合物在医药、材料、合成化学等领域具有广泛的应用,其合成方法一直是有机化学工作者们的研究热点。可见光催化具有成本低、易获得和环境友好等特点,其诱导的磺酰基自由基反应已成为合成砜类化合物的重要手段。磺酰氯廉价、易获得、种类多,是一类重要的磺酰基自由基前体。本文介绍了近年来在可见光催化下,磺酰氯参与的C-磺酰基化合物的合成研究进展。按照可见光催化剂种类如Ir配合物、Ru配合物、无外加光敏剂以及其他类型光催化剂等进行分类归纳讨论,并对相应的反应机理进行了阐述,为今后此类反应在有机合成中的应用提供参考,并指出该领域研究面临的挑战及发展方向。     

NIR‐Light‐Activated Combination Therapy with a Precise Ratio of Photosensitizer and Prodrug Using a Host–Guest Strategy

The co‐delivery of photosensitizers with prodrugs sensitive to reactive oxygen species (ROS) for light‐triggered ROS generation and cascaded prodrug activation has drawn tremendous attention. However, the absence of a feasible method to deliver the two components at a precise ratio has impaired the application potential. Herein, we report an efficient method to produce a nanosized platform for the delivery of an optimized ratio of the two components by the means of host–guest strategy for maximizing the combination therapy efficacy of cancer treatment. The key features of this host–guest strategy for the combination therapy are that the ratio between photosensitizer and ROS‐sensitive prodrug can be easily tuned, near‐infrared (NIR) irradiation can sensitize the photosensitizer and activate the paclitaxel prodrug for its release, and the accumulation process can be tracked by NIR imaging to maximize the efficacy of photodynamic and chemotherapy.     

Catalytic Conversion of Dinitrogen into Ammonia under Ambient Reaction Conditions by Using Proton Source from Water

Molybdenum‐catalyzed conversion of molecular dinitrogen into ammonia under ambient reaction conditions has been achieved by using a proton source generated in situ from the ruthenium‐catalyzed oxidation of water in combination with visible light and a photosensitizer. The preset reaction system is considered as a new model for the nitrogen fixation by photosynthetic bacteria.     

Long conjugated 2-nitrobenzyl derivative caged anticancer prodrugs with visible light regulated release: preparation and functionalizations

A series of anticancer prodrugs with different chemical functional groups were prepared, in which the styryl conjugated 2-nitrobenzyl derivatives were introduced as the phototrigger to regulate the drug (chlorambucil) release. Compared to the common 4,5-dimethoxy-2-nitrobenzyl caged compounds, most of the prodrugs exhibited large and redshifted one-photon absorption within the visible range. One-photon excitation for the drug release was studied by measuring UV-vis absorption, FT-IR, and HPLC spectra, which suggested that chlorambucil was released effectively and precisely by manipulating external light conditions. And the introduction of different functional groups made this type of prodrug a good platform to further react with some typical drug carriers and to further form excellent visible light responsive drug delivery systems. Moreover, the drug also could be effectively released under the excitation of two-photon at 800 nm with comparable photorelease efficiencies.     

Supramolecular nanoparticles constructed by orthogonal assembly of pillar[5]arene-cyclodextrin dimacrocycle for chemo-photodynamic combination therapy

Chemotherapy combined with photodynamic therapy has emerged as a promising strategy for cancer treatment. However, simultaneously delivering chemotherapeutic drugs and photosensitizers and precisely adjusting the ratio of the two components as needed remains a challengeable task. Herein, novel supramolecular nanoparticles (donated as BODIPY-CPT-NPs) for chemo-photodynamic combination cancer therapy are constructed from a glutathione-responsive camptothecin-based prodrug, BODIPY photosensitizer, and dimacrocyclic host molecule through orthogonal host-guest recognitions and co-assembly. With this strategy, the ratio of prodrugs and photosensitizers in nanoparticles can be easily and precisely controlled as needed. Benefiting from the strong host-guest interactions and stable self-assembly, the nanoparticles exhibit excellent stability and photobleaching resistance. Furthermore, camptothecin can be released from nanoparticles for chemotherapy in the presence of reduction agent and single oxygen can be efficiently generated for PDT with light irradiation. The combined effects of the BODIPY-CPT-NPs have been verified in CT26 and HeLa cancer cells.     

4-(4-甲基-苯基)-6-苯基-2,2′-联吡啶铂(Ⅱ)光致产氢研究

本文以氯离子配位的4-(4-甲基-苯基)-6-苯基-2,2′-联吡啶铂(Ⅱ)配合物为光敏剂,Co(dmgH)2pyCl为催化剂,三乙醇胺(TEOA)为电子牺牲体,在pH为8.5的乙腈/水混合溶剂中构建了光致产氢体系.体系光照(λ>400nm)19h后产氢量达到1.8mL,反应的转换数(TON)达到804(vs.光敏剂).     

Visible-Light Augmented Lithium Storage Capacity in a Ruthenium(II) Photosensitizer Conjugated with a Dione-Catechol Redox Couple

Controlling redox activity of judiciously appended redox units on a photo-sensitive molecular core is an effective strategy for visible light energy harvesting and storage. The first example of a photosensitizer - electron donor coordination compound in which the photoinduced electron transfer step is used for light to electrical energy conversion and storage is reported. A photo-responsive Ru-diimine module conjugated with redox-active catechol groups in [Ru(II)(phenanthroline-5,6-diolate)₃]⁴⁻ photosensitizer can mediate photoinduced catechol to dione oxidation in the presence of a sacrificial electron acceptor or at the surface of an electrode. Under potentiostatic condition, visible light triggered current density enhancement confirmed the light harvesting ability of this photosensitizer. Upon implementation in galvanostatic charge-discharge of a Li battery configuration, the storage capacity was found to be increased by 100 %, under 470 nm illumination with output power of 4.0 mW/cm⁻². This proof-of-concept molecular system marks an important milestone towards a new generation of molecular photo-rechargeable materials.     

长波长光敏引发聚合体系

香豆素酮染料;双咪唑;染料增感;长波长光敏引发聚合体系     

Visible light-induced nuclease activity of a ternary mono-phenanthroline copper(II) complex containing L-methionine as a photosensitizer

Ternary copper(II) complex, structurally characterized as [Cu(phen)(met)(MeOH)](ClO4) (1) by X-ray crystallography, has 1,10-phenanthroline (phen) as an intercalator/binder to supercoiled pUC19 DNA and L-methionine (met) as a photosensitizer, and the complex displays efficient photonuclease activity on irradiation with UV (312 nm) or visible (436, 532 nm) light through a mechanistic pathway involving singlet oxygen.     

Impact of ligand exchange in hydrogen production from cobaloxime-containing photocatalytic systems

Ligand exchange on the Co(dmgH)(2)(py)Cl water reduction catalyst was explored under photocatalytic conditions. The photosensitizer fluorescein was connected to the catalyst through the axially coordinated pyridine. While this two-component complex produces H(2) from water under visible light irradiation in the presence of triethanolamine (TEOA), it is less active than a system containing separate fluorescein and [Co(III)(dmgH)(2)(py)Cl] components. NMR and photolysis experiments show that the Co catalyst undergoes pyridine exchange. Interestingly, glyoximate ligand exchange was also observed photocatalytically and by NMR spectroscopy, thereby showing that integrated systems in which the photosensitizer is linked directly to the Co(dmgH)(2)(py)Cl catalyst may not remain intact during H(2) photogeneration. These studies have also given rise to insights into the catalyst decomposition mechanism.     

Visible‐Light‐Driven Intermolecular [2+2] Cycloadditions between Coumarin‐3‐Carboxylates and Acrylamide Analogs

This paper reports a room temperature visible‐light‐driven protocol for the intermolecular [2+2] cycloadditions between coumarin‐3‐carboxylates and acrylamides analogs by an energy‐transfer process. Using an iridium complex FIrPic as a photosensitizer and a 3 W blue LED as a light source, an array of cyclobutabenzocypyranones were prepared in moderate to excellent yields.     

Hydrogen Production on a Hybrid Photocatalytic System Composed of Ultrathin CdS Nanosheets and a Molecular Nickel Complex

The production of clean and renewable hydrogen through water splitting by using solar energy has received much attention due to the increasing global energy demand. We report an economic and artificial photosynthetic system free of noble metals, consisting of ultrathin CdS nanosheets as a photosensitizer and nickel‐based complex as a molecular catalyst. Emission quenching and flash photolysis studies reveal that this hybrid system allows for effective electron transfer from the excited CdS nanosheets to the nickel‐based complex to generate reduced intermediate species for efficient hydrogen evolution. Notably, the unique morphological and structural features of the ultrathin CdS nanosheets contribute to the highly efficient photocatalytic performance. As a consequence, the resulting system shows exceptional activity and stability for photocatalytic hydrogen evolution in aqueous solution with a turnover number (TON) of about 28 000 versus catalyst and a lifetime of over 90 h under visible light irradiation.     

Transient Spectroscopy of 5,7‐diiodo‐3‐butoxy‐6‐fluorone (DIBF)

DIBF (5,7‐diiodo‐3‐butoxy‐6‐fluorone) is a visible light photosensitizer for diaryliodonium salts, the latter being used in cationic photopolymerizations. Although photopolymerization of cycloaliphatic epoxide resins can be initiated by direct excitation of UV‐absorbing diaryliodonium salts, such as (p‐octyloxy)phenyliodonium hexafluoroantimonate (OPPI), the short wavelengths required cause some practical problems. Sensitizers, of which DIBF is among the best, obviate the deep UV problem by allowing visible‐wavelength activation of the photoinitiator. Addition of 9,10‐diethoxyanthracene (AN 910 E) dramatically accelerates photopolymerization under visible irradiation of the DIBF/OPPI system. We report herein the transient spectroscopy of the photosensitizer DIBF and discuss likely mechanisms for sensitization of OPPI.     

A Nucleic Acid Dependent Chemical Photocatalysis in Live Human Cells

Only two nucleic acid directed chemical reactions that are compatible with live cells have been reported to date. Neither of these processes generate toxic species from nontoxic starting materials. Reactions of the latter type could be applied as gene‐specific drugs, for example, in the treatment of cancer. We report here the first example of a chemical reaction that generates a cytotoxic drug from a nontoxic prodrug in the presence of a specific endogeneous ribonucleic acid in live mammalian cells. In this case, the prodrug is triplet oxygen and the drug is singlet oxygen. The key component of this reaction is an inert molecule (InP–2′‐OMe‐RNA/Q–2′‐OMe‐RNA; P: photosensitizer; Q: quencher), which becomes an active photosensitizer (InP–2′‐OMe‐RNA) in the presence of single‐stranded nucleic acid targets. Upon irradiation with red light, the photosensitizer produces over 6000 equivalents of toxic singlet oxygen per nucleic acid target. This reaction is highly sequence specific. To detect the generation of singlet oxygen in live cells, we prepared a membrane‐permeable and water‐soluble fluorescent scavenger, a derivative of 2,5‐diphenylisobenzofurane. The scavenger decomposes upon reaction with singlet oxygen and this is manifested in a decrease in the fluorescence intensity. This effect can be conveniently monitored by flow cytometry.     

Light‐Harvesting Photocatalysis for Water Oxidation Using Mesoporous Organosilica

An organic‐based photocatalysis system for water oxidation, with visible‐light harvesting antennae, was constructed using periodic mesoporous organosilica (PMO). PMO containing acridone groups in the framework (Acd‐PMO), a visible‐light harvesting antenna, was supported with [Ru^II(bpy)₃²⁺] complex (bpy=2,2′‐bipyridyl) coupled with iridium oxide (IrO_x) particles in the mesochannels as photosensitizer and catalyst, respectively. Acd‐PMO absorbed visible light and funneled the light energy into the Ru complex in the mesochannels through excitation energy transfer. The excited state of Ru complex is oxidatively quenched by a sacrificial oxidant (Na₂S₂O₈) to form Ru³⁺ species. The Ru³⁺ species extracts an electron from IrO_x to oxidize water for oxygen production. The reaction quantum yield was 0.34 %, which was improved to 0.68 or 1.2 % by the modifications of PMO. A unique sequence of reactions mimicking natural photosystem II, 1) light‐harvesting, 2) charge separation, and 3) oxygen generation, were realized for the first time by using the light‐harvesting PMO.     

Direct Photocontrol of Peptidomimetics: An Alternative to Oxygen‐Dependent Photodynamic Cancer Therapy

Conventional photodynamic treatment strategies are based on the principle of activating molecular oxygen in situ by light, mediated by a photosensitizer, which leads to the generation of reactive oxygen species and thereby causes cell death. A diarylethene‐derived peptidomimetic is presented that is suitable for photodynamic cancer therapy without any involvement of oxygen. This light‐sensitive molecule is not a mediator but is itself the cytotoxic agent. As a derivative of the cyclic amphiphilic peptide gramicidin S, the peptidomimetic exists in two thermally stable photoforms that are interconvertible by light of different wavelengths. The isomer generated by visible light shows much stronger toxicity against tumor cells than the UV‐generated isomer. First in vivo applications are demonstrated on a tumor animal model to illustrate how the peptidomimetic can be administered in the less toxic form and then activated locally in a solid tumor by visible light.     

Sensitized Photochemical CO2 Reduction by Hetero-Pacman Compounds Linking a ReI Tricarbonyl with a Porphyrin Unit

The hetero-Pacman architecture places two different metal coordination sites in close proximity, which can support efficient energy and/or electron transfer and allow for cooperative activation of small molecules. Here, the synthesis of dyads consisting of a porphyrin unit as photosensitizer and a rhenium unit as catalytically active site, which are held together by the rigid xanthene backbone, is presented. Mononuclear [(NN)Re(CO)₃(Cl)] complexes for CO₂ reduction in which NN represents a bidentate diimine ligand (e.g., bipyridine or phenanthroline) lack light absorption in the visible region, resulting in poor photocatalysis upon illumination with visible light. To improve their visible-light absorption, we have focused on the incorporation of a strongly absorbing free base or zinc porphyrin unit. Resulting photocatalytic experiments showed a strong dependence of the catalytic performance on both the type of photosensitizer and the excitation wavelengths. Most notably, the intramolecular hetero-Pacman system containing a zinc porphyrin unit showed much better catalytic activity in the visible region (excitation wavelengths >450 nm) than the free base porphyrin version or the corresponding mononuclear rhenium compound or an intermolecular system comprised of a 1:1 mixture of the mononuclear analogues.     

Near‐Infrared Light‐Mediated Photoactivation of a Platinum Antitumor Prodrug and Simultaneous Cellular Apoptosis Imaging by Upconversion‐Luminescent Nanoparticles

Platinum‐based drugs are among the most active antitumor reagents in clinical practice; their application is limited by side effects and drug resistance. A novel and personalized near‐infrared (NIR) light‐activated nanoplatform is obtained by combining a photoactivatable platinum(IV) prodrug and a caspase imaging peptide conjugated with silica‐coated upconversion‐luminescent nanoparticles (UCNPs) for the remote control of antitumor platinum prodrug activation, and simultaneously for real‐time imaging of apoptosis induced by activated cytotoxicity. Upon NIR light illumination, the Pt^IV prodrug complex is activated at the surface of the nanoparticle and active components are selectively released which display cytotoxicity against human ovarian carcinoma A2780 cells and its cisplatin‐resistant variant A2780cis cells. More importantly, the caspases enzymes triggered by cytotoxicity would effectively cleave the probe peptide, thereby allowing the direct imaging of apoptosis in living cells.     

Effect of visible light on selected enzymes, vitamins and amino acids.

In most cases, the presence of an endogenous photosensitizer is a requirement for visible light modification of biomolecules in animal tissues. Riboflavin (RF) is present in all aerobic cells and is a very efficient photosensitizer, presenting a complex photochemistry with a mixed type I-type II mechanisms. Visible light irradiation in the presence of RF diminished the enzymatic activity of horse radish peroxidase (HRP) only when this glyco-enzyme was deglycosilated. In contrast, the activity of catalase is inactivated via singlet oxygen, and that of lysozyme was efficiently inactivated by a mixed type I-type II mechanisms. The reactive species involved in the RF sensitized photoconversion of lysozyme and the aromatic amino acids tryptophan and tyrosine (both free in solution) is discussed. The role of ascorbate and the effect of RF photosensitized processes in biological complex systems, such as the ocular lens and tumoral cell in culture, is analyzed.     

Activation by Glutathione in Hypoxic Environment of an Azo-based Rhodamine Activatable Photosensitizer. A Computational Elucidation

In the present paper, density functional theory (DFT) has been applied to the study of the activation mechanism of a new selenium azo-rhodamine (azoSeRho) in presence of the tripeptide thiol, glutathione (GSH), as potent activatable photosensitizer to be employed in photodynamic therapy. The introduction of the azo group into the conjugated system of the seleno-rhodamine dye and its reaction with GSH allow the selective formation of the active photosensitizer, SeRho. Furthermore, DFT calculations have allowed to shed light on the activation mechanism of the azoSeRho photosensitizer when molecular oxygen is present and hydrogen peroxide is formed. This study is the first theoretical investigation revealing how the reductive cleavage of the azo moiety by GSH occurs. Time-dependent DFT approach has been used to evaluate the chalcogen-substitution effect on the structures and photophysical properties of the azo derivatives and, then, on the activated photosensitizers.