紫外光诱导氧合型肌红蛋白氧化反应及机理

肌红蛋白通常在无光条件下可进行输氧、储氧等重要功能,实验中我们发现紫外光照射可促进氧合肌红蛋白(MbO₂)的氧化反应,证实其在光照时部分生理功能会发生变化。紫外-可见(UV-Vis)吸收光谱数据显示,光照射时MbO₂的Soret带最大吸收波长蓝移、Q吸收带544和580 nm处还原峰强度下降,说明紫外光光照促进O₂解离, MbFe(Ⅱ)可被氧化至MbFe(Ⅲ)。四种波长光对光照氧化的影响程度为254 nm > 280 nm >430 nm > 409 nm;通入CO气体时氧合肌红蛋白较难发生光照氧化反应,即Fe的第六配位强度影响反应程度;溶液中的H⁺或OH^-对光照氧化反应有促进作用; 254、280 nm波长光照射时,苯丙氨酸(Phe)、酪氨酸(Tyr)、色氨酸(Trp)三种游离氨基酸均促进光照氧化反应的进行,而409、430 nm波长光照射时三种游离氨基酸对光照氧化反应的影响较小。以上数据表明体内光诱导MbO₂氧化反应过程中蛋白质内的Fe(Ⅱ)能否被光照激发形成未成对电子处于激发态是O₂离去和二价铁被氧化的关键。     

Manganese carbonyls bearing tripodal polypyridine ligands as photoactive carbon monoxide-releasing molecules

The recently discovered cytoprotective action of CO has raised interest in exogenous CO-releasing materials (CORMs) such as metal carbonyls (CO complexes of transition metals). To achieve control on CO delivery with metal carbonyls, we synthesized and characterized three Mn(I) carbonyls, namely, [Mn(tpa)(CO)(3)]ClO(4) [1, where tpa = tris(2-pyridyl)amine], [Mn(dpa)(CO)(3)]Br [2, where dpa = N,N-bis(2-pyridylmethyl)amine], and [Mn(pqa)(CO)(3)]ClO(4) [3, where pqa = (2-pyridylmethyl)(2-quinolylmethyl)amine], by crystallography and various spectroscopic techniques. All three carbonyls are sensitive to light and release CO when illuminated with low-power UV (5-10 mW) and visible (λ > 350 nm, ~100 mW) light. The sensitivity of 1-3 to light has been assessed with respect to the number of pyridine groups in their ligand frames. When a pyridine ring is replaced with quinoline, extended conjugation in the ligand frame increases the absorptivity and makes the resulting carbonyl 3 more sensitive to visible light. These photosensitive CORMs (photoCORMs) have been employed to deliver CO to myoglobin under the control of light. The superior stability of 3 in aqueous media makes it a photoCORM suitable for inducing vasorelaxation in mouse aortic muscle rings.     

Phosphorus‐containing Salen‐metal complexes investigated for enhancing the fire safety of thermoplastic polyurethane (TPU)

Three novel phosphorus‐containing Salen‐based derivatives (Salen‐DPCP‐M: M = Ni, Zn, and Mn), which include both phenyl phosphate structures (DPCP) and Salen‐metal complexes, were prepared for enhancing the fire safety of thermoplastic polyurethane (TPU). Thermogravimetric analysis (TGA) showed that Salen‐DPCP‐M altered the thermal degradation pathways of TPU probably due to the phosphorus‐containing structure of Salen‐DPCP‐M. The cone calorimeter test showed that the addition of 3 wt% of Salen‐DPCP‐Ni, Salen‐DPCP‐Zn, and Salen‐DPCP‐Mn lowered the peak of heat release rate (PHRR) from 1495 kW/m² for neat TPU to 690, 875, and 813 kW/m², respectively, for the TPU composites, which demonstrated that Salen‐DPCP‐M improved the fire safety of TPU. In addition, the release of toxic CO gas from the Salen‐DPCP‐Ni/TPU and Salen‐DPCP‐Zn/TPU composites was reduced by 78.2% and 80.0%, respectively. The results of TGA/infrared spectrometry (TG‐FTIR) showed that the incorporation of Salen‐DPCP‐Ni promoted the release CO₂, while reducing the formation of harmful gases. Laser Raman spectroscopy (LRS) and scanning electron microscopy (SEM) showed that Salen‐DPCP‐Ni/TPU and Salen‐DPCP‐Zn/TPU composites formed a dense and stable char layer. Herein, the mechanism of these flame retardants containing novel phosphorus‐containing Salen‐metal complexes is also proposed.     

Anticancer activities of manganese-based photoactivatable CO-releasing complexes (PhotoCORMs) with benzimidazole derivative ligands

Carbon monoxide is an important signaling molecule which is produced by heme oxygenase-1. CO shows antiproliferative activity against cancer cells; hence, activation of HO-1 is a significant inhibition strategy against tumor formation and survival of cancer cells. In this work, manganese-based CO-releasing molecules (CORMs) were designed and synthesized to inhibit breast cancer cell proliferation. Human invasive ductal breast cancer cells (MCF-7) were treated with the synthesized CORMs to investigate the effect of the complexes on breast cancer survival under UV light. In vitro experiments indicated that the complexes inhibited breast cancer cell proliferation, and further, the antiproliferative effects were increased under UV light. Thus, these novel CORMs may provide a drug template for the treatment of invasive ductal breast cancer.     

Cyanine-Flavonol Hybrids for Near-Infrared Light-Activated Delivery of Carbon Monoxide

Carbon monoxide (CO) is an endogenous signaling molecule that controls a number of physiological processes. To circumvent the inherent toxicity of CO, light-activated CO-releasing molecules (photoCORMs) have emerged as an alternative for its administration. However, their wider application requires photoactivation using biologically benign visible and near-infrared (NIR) light. In this work, a strategy to access such photoCORMs by fusing two CO-releasing flavonol moieties with a NIR-absorbing cyanine dye is presented. These hybrids liberate two molecules of CO in high chemical yields upon activation with NIR light up to 820 nm and exhibit excellent uncaging cross-sections, which surpass the state-of-the-art by two orders of magnitude. Furthermore, the biocompatibility and applicability of the system in vitro and in vivo are demonstrated, and a mechanism of CO release is proposed. It is hoped that this strategy will stimulate the discovery of new classes of photoCORMs and accelerate the translation of CO-based phototherapy into practice.     

Metal-free carbon monoxide-releasing micelles undergo tandem photochemical reactions for cutaneous wound healing

Carbon monoxide (CO) has shown broad biomedical applications. The site-specific delivery and controlled release of CO is of crucial importance to achieve maximum therapeutic benefits. The development of carbon monoxide (CO)-releasing polymers (CORPs) can increase the stability, optimize pharmacokinetic behavior, and reduce the side effects of small molecule precursors. However, almost all established CORPs were synthesized through a post functional approach, although the direct polymerization strategy is more powerful in controlling the chain compositions and architectures. Herein, a direct polymerization strategy is proposed toward metal-free CO-releasing polymers (CORPs) based on photoresponsive 3-hydroxyflavone (3-HF) derivatives. Such CO-releasing amphiphiles self-assemble into micelles, having excellent water-dispersity. Intriguingly, photo-triggered tandem photochemical reactions confer successive fluorescence transitions from blue-to-red-to-colorless, enabling self-reporting CO release in vitro and in vivo as a result of the incorporation of 3-HF derivatives. More importantly, the localized CO delivery of CORPs by taking advantage of the spatiotemporal control of light stimulus outperformed conventional metal carbonyls such as CORMs in terms of anti-inflammation and cutaneous wound healing. This work opens a novel avenue toward metal-free CORPs for potential biomedical applications.

Metal-free carbon monoxide-releasing polymers (CORPs) are synthesized via a direct polymerization approach, exhibiting not only improved stability but also accelerated wound healing performance as compared to CORM-3.     

CO气氛下褐煤加压快速热解过程中CH_4的逸出规律

在管式反应器上进行了霍林河褐煤加压快速热解实验,研究了CO气氛下CH4逸出规律。在加压快速热解条件下,由于CO解离态吸附的O(a)吸附在煤上,提供了活性中心,电负性强的O(a)诱发其周围其他原子的电子云向O(a)偏移,减弱了原来化学键的强度,导致芳香环的开裂,侧链、醚键和脂肪链的断裂提供更多的自由基,稳定煤热解生成的碎片,促进了CH4的生成和逸出。因此,CO气氛下CH4产率较N2气氛下的高,在900℃、1.0 MPa时,50%CO气氛下的CH4产率较N2气氛下的提高了12.5%,并且CH4产率随着温度升高、压力的增大而增大。     

The application of BTEM to UV-vis and UV-vis CD spectroscopies: the reaction of Rh4(CO)12 with chiral and achiral ligands

Two different organometallic ligand substitution reactions were investigated: (1) an achiral reactive system consisting of Rh₄(CO)₁₂ + PPh₃  Rh₄(CO)₁₁PPh₃ + CO in n-hexane under argon; and (2) a chiral reactive system consisting of Rh₄(CO)₁₂ + (S)-BINAP  Rh₄(CO)₁₀BINAP + 2CO in cyclohexane under argon. These two reactions were run at ultra high dilution. In both multi-component reactive systems the concentrations of all the solutes were less than 40 ppm and many solute concentrations were just 1–10 ppm. In situ spectroscopic measurements were carried out using UV–vis (Ultraviolet–visible) spectroscopy and UV–vis CD spectroscopy on the reactive organometallic systems (1) and (2), respectively. The BTEM algorithm was applied to these spectroscopic data sets. The reconstructed UV–vis pure component spectra of Rh₄(CO)₁₂, Rh₄(CO)₁₁PPh₃ and Rh₄(CO)₁₀BINAP as well as the reconstructed UV–vis CD pure component spectra of Rh₄(CO)₁₀BINAP were successfully obtained from BTEM analyses. All these reconstructed pure component spectra are in good agreement with the experimental reference spectra. The concentration profiles of the present species were obtained by performing a least square fit with mass balance constraints for the reactions (1) and (2). The present results indicate that UV–vis and UV–vis-CD spectroscopies can be successfully combined with an appropriate chemometric technique in order to monitor reactive organometallic systems having UV and Vis chromophores.     

Designed iron carbonyls as carbon monoxide (CO) releasing molecules: rapid CO release and delivery to myoglobin in aqueous buffer, and vasorelaxation of mouse aorta

The physiological roles of CO in neurotransmission, vasorelaxation, and cytoprotective activities have raised interest in the design and syntheses of CO-releasing materials (CORMs) that could be employed to modulate such biological pathways. Three iron-based CORMs, namely, [(PaPy(3))Fe(CO)](ClO(4)) (1), [(SBPy(3))Fe(CO)](BF(4))(2) (2), and [(Tpmen)Fe(CO)](ClO(4))(2) (3), derived from designed polypyridyl ligands have been synthesized and characterized by spectroscopy and X-ray crystallography. In these three Fe(II) carbonyls, the CO is trans to a carboxamido-N (in 1), an imine-N (in 2), and a tertiary amine-N (in 3), respectively. This structural feature has been correlated to the strength of the Fe-CO bond. The CO-releasing properties of all three carbonyls have been studied in various solvents under different experimental conditions. Rapid release of CO is observed with 2 and 3 upon dissolution in both aqueous and nonaqueous media in the presence and absence of dioxygen. With 1, CO release is observed only under aerobic conditions, and the final product is an oxo-bridged diiron species while with 2 and 3, the solvent bound [(L)Fe(CO)](2+) (where L = SBPy(3) or Tpmen) results upon loss of CO under both aerobic and anaerobic conditions. The apparent rates of CO loss by these CORMs are comparable to other CORMs such as [Ru(glycine)(CO)(3)Cl] reported recently. Facile delivery of CO to reduced myoglobin has been observed with both 2 and 3. In tissue bath experiments, 2 and 3 exhibit rapid vasorelaxation of mouse aorta muscle rings. Although the relaxation effect is not inhibited by the soluble guanylate cyclase inhibitor ODQ, significant inhibition is observed with the BK(Ca) channel blocker iberiotoxin.     

Carbon monoxide-releasing micelles for immunotherapy

With the discovery of important biological roles of carbon monoxide (CO), the use of this gas as a therapeutic agent has attracted attention. However, the medical application of this gas has been hampered by the complexity of the administration method. To overcome this problem, several transition-metal carbonyl complexes, such as Ru(CO)(3)Cl(glycinate), [Ru(CO)(3)Cl(2)](2), and Fe(η(4)-2-pyrone)(CO)(3), have been used as CO-releasing molecules both in vitro and in vivo. We sought to develop micellar forms of metal carbonyl complexes that would display slowed diffusion in tissues and thus better ability to target distal tissue drainage sites. Specifically, we aimed to develop a new CO-delivery system using a polymeric micelle having a Ru(CO)(3)Cl(amino acidate) structure as a CO-releasing segment. The CO-releasing micelles were prepared from triblock copolymers composed of a hydrophilic poly(ethylene glycol) block, a poly(ornithine acrylamide) block bearing Ru(CO)(3)Cl(ornithinate) moieties, and a hydrophobic poly(n-butylacrylamide) block. The polymers formed spherical micelles in the range of 30-40 nm in hydrodynamic diameter. Further characterization revealed the high CO-loading capacity of the micelles. CO-release studies showed that the micelles were stable in physiological buffer and serum and released CO in response to thiol-containing compounds such as cysteine. The CO release of the micelles was slower than that of Ru(CO)(3)Cl(glycinate). In addition, the CO-releasing micelles efficiently attenuated the lipopolysaccharide-induced NF-κB activation of human monocytes, while Ru(CO)(3)Cl(glycinate) did not show any beneficial effects. Moreover, cell viability assays revealed that the micelles significantly reduced the cytotoxicity of the Ru(CO)(3)Cl(amino acidate) moiety. This novel CO-delivery system based on CO-releasing micelles may be useful for therapeutic applications of CO.     

在Pd/TiO2上CO的光催化增强效应

在Pd(2％)/TiO2上CO催化氧化的研究中发现：室温下， 以黑光灯（λ=365 nm）照时， CO的氧化活性比暗态显著提高，产生了明显的光催化增强效应（两者速率常数比约为15）.但在TiO2上，无论暗态还是黑光灯（λ=365 nm）照，均无CO氧化反应发生.这可能是由于氧分子解离吸附时的键能减弱，使Pd表面氧原子（或O－）浓度增加和氧原子的溢流（oxygen spillover）两种效应结合产生的.     

TiO2和ZnO表面CO光催化氧化活性研究

在TiO2和ZnO表面CO光催化氧化研究中发现,365 nm紫外光照下TiO2表面无活性,而ZnO表面却有明显的CO光催化氧化活性.研究表明,主要是由于紫外光照下,ZnO光分解而TiO2没有光分解,从而在表面产生不同吸附形态的氧所致.而且,ZnO表面CO光催化氧化反应活性可在27 h内保持稳定,暗示气相光催化反应中,ZnO不会因为光腐蚀而使其催化活性降低.     

基于席夫碱配体的锰羰基配合物可见光诱导释放一氧化碳性能

利用五羰基溴化锰和2-吡啶甲醛以及卤代苯胺通过一步法合成得到了3个含席夫碱配体的锰羰基配合物[Mn(CO)₃(py(CH=N)ph-X)Br],其中X=Cl (1)、Br (2)、I (3),并采用核磁、X射线单晶衍射、红外光谱、紫外可见光谱和荧光光谱对其进行了表征。这类配合物在非光照下稳定,在可见光(LED蓝光、绿光和红光)作用下分解释放CO,可以作为光诱导的一氧化碳释放剂(photoCORMs)。研究表明蓝光是促进配合物分解释放CO的最有效光源。此外,CO释放动力学分析显示配合物分解释放CO过程符合一级动力学模型。配合物3的释放研究表明脱氧肌红蛋白能够捕捉所释放的CO。尽管这些配合物本身的细胞毒性(IC50)达到微摩尔级,但光照下的细胞兼容性有显著改善,上升为接近100微摩尔级。这些配合物具有荧光性质,在450 nm激发波长下在500～700 nm范围内发射一定强度的荧光,可以作为荧光标记物用以监测细胞或生物体内释放剂分布及CO释放情况。     

Femtosecond absorption study of photodissociation of diphenylcyclopropenone in solution: reaction dynamics and coherent nuclear motion

Reaction dynamics and coherent nuclear motions in the photodissociation of diphenylcyclopropenone (DPCP) were studied in solution by time-resolved absorption spectroscopy. Subpicosecond transient absorption spectra were measured in the visible region with excitation at the second absorption band of DPCP. The obtained spectra showed a new short-lived band around 480 nm immediately after photoexcitation, which is assignable to the initially populated S(2) state of DPCP before the dissociation. The dissociation takes place from this excited state (the precursor of the reaction) with a time constant of 0.2 ps, and the excited state of diphenylacetylene (DPA) is generated as the reaction product. The transient absorption after the dissociation decayed with a time constant of 8 ps that is very close to the S(2)-state lifetime of DPA, but the spectrum of this 8-ps component was different from the S(2) absorption observed with direct photoexcitation of DPA. We conclude that the dissociation of DPCP generates the S(2) state of DPA that probably has a cis-bent structure. At later delay times (>30 ps), the transient absorption signals are very similar to those obtained by direct photoexcitation of DPA. This confirmed that the electronic relaxation from the S(2) state of the product DPA occurs in a similar manner to that of DPA itself, i.e., the internal conversion to the S(1) state and subsequent intersystem crossing to the T(1) state. In order to examine the coherent nuclear dynamics in this dissociation reaction, we carried out time-resolved absorption measurements for the 480-nm band with 70 fs resolution. It was found that an underdamped oscillatory modulation with a 0.1-ps period is superposed on the decay of the precursor absorption. This indicates that DPCP exhibits a coherent nuclear motion having a approximately 330-cm(-1) frequency in the dissociative excited state. Based on a comparison with the measured and calculated Raman spectra of ground-state DPCP, we discuss the assignment of the "330-cm(-1) vibration" and attribute it to a vibration involving the displacement of the CO group as well as the deformation of the Ph-C[Double Bond]C-Ph skeleton. We consider that this motion is closely related to the reaction coordinate of the photodissociation of DPCP.     

Chemistry and biological activities of CO-releasing molecules (CORMs) and transition metal complexes

The advent of CO as a small molecule that, in addition to NO, elicits essential biological functions has initiated the search for compounds and complexes capable of releasing CO in a well defined manner under physiological conditions. Since some pharmacological and therapeutic effects of CO have been established in preclinical studies, tailor-made CO-releasing molecules (CORMs) which could be utilized as pharmaceuticals could be of great benefit for many patients. Release of CO(2) is one of the most common features in chemistry and NO producing molecules are very well established but compounds with CO-releasing properties are rare. Some of the more promising candidates and molecules under study are discussed in this article. Furthermore, molecules that possess intrinsic features to serve as potential CO-RMs and merit in depth investigations are proposed. The focus is thereby on main group compounds and on transition element complexes. It should be emphasized that CORMs not only have encouraging prospects as therapeutic agents but may also be significant for synthetic pathways to novel complexes containing the CO ligand. To underline the prospects of CORMs, the chemical part is embedded in a biological and medicinal context.     

可见光诱导提升Pt/g-C3N4纳米片甲酸氧化性能的研究

以半导体材料类石墨氮化碳纳米片(g-C₃N₄纳米片)为载体,通过微波-多元醇法构筑了Pt/g-C₃N₄纳米片催化剂. 通过TEM、XRD、XPS、紫外-可见吸收光谱等方法对Pt/g-C₃N₄纳米片催化剂的粒径尺寸、组成、结构、光学等性质进行分析. 通过对比可见光照和暗室条件下的甲酸电氧化活性,Pt/g-C₃N₄纳米片催化剂在可见光照射下展现出良好的催化性能. 该性能的提高一方面可能是由于g-C₃N₄纳米片在可见光照射下加速了电子从Pt转移给g-C₃N₄纳米片,Pt处于“电子匮乏”状态,可削弱CO与Pt之间的化学键能,减弱CO在Pt表面的吸附能力,促进了CO的氧化,提高了催化剂抗中毒能力;另一方面,g-C₃N₄纳米片在光照条件下分离出的空穴可有效氧化甲酸分子,提高甲酸氧化活性. 因此,可见光条件下可有效提高Pt/g-C₃N₄纳米片催化剂甲酸催化氧化活性,这为直接甲酸燃料电池的发展提供了新思路.     

含二齿膦配体的二羰基铁化合物的制备及光诱导释放一氧化碳性能

一氧化碳释放剂(CORM)为CO在人体的精准输送提供了便利。为提高CORM的稳定性,以[Fe(CO)₄I₂]为前驱体,通过与二齿膦配体dppe、dppp、PNP(dppe=1,2-双(二苯基膦酰)乙烷,dppp=1,3-双(二苯基膦酰)丙烷,PNP=N-环己基-N-(二苯基膦酰)-1,1-二苯基膦胺(Ph₂PN(cyclohexyl)PPh₂)的配位取代反应制得了二齿膦二羰基铁化合物1~3,并利用FT-IR、UV-Vis、NMR、元素分析、单晶X射线衍射(化合物2、3)进行表征。通过红外光谱法研究了化合物1~3的降解释放CO性能,以评估其作为CORM的潜能。在二甲亚砜溶剂中、黑暗条件下这些化合物表现出良好稳定性;但在可见光(红光、绿光、蓝光)照射下,均可降解释放CO,其降解速率与光源的能量和化合物的结构有关。此外,在蓝光和绿光照射下,发现化合物1和2可从顺式构型向反式构型发生转化,而红光下因能量不足未见构型转化。     

High open-circuit voltage in UV photovoltaic cell based on polymer/inorganic bilayer structure

Polymer/inorganic hybrid ultra violet (UV) photovoltaic device is fabricated by using poly(N-vinyl-carbazole) (PVK) and zinc sulfide (ZnS). The device shows promising photovoltaic characteristics with a high open-circuit voltage of 1.65 V, and a short-circuit current of 46.8 μA/cm² under the illumination of 340 nm UV light with the intensity of 14 mW/cm². Besides, much correlative photocurrent spectra of the device under forward and reverse applied bias manifest the transport mechanism of charge carriers in PVK/ZnS bilayer systems.     

Photochemical degradation of environmentally persistent perfluorooctanoic acid （PFOA） in the presence of Fe（Ⅲ）

Environmentally persistent and bioaccumulative perfluorooctanic acid （PFOA） was difficult to be decomposed under the irradiation of 254 nm UV light. However, in the presence of 80μmol/L Fe（Ⅲ）, 80% of PFOA with initial concentration of 48μmol/L （20 mg/L） was effectively degraded and 47.8% of fluorine atoms in PFOA molecule were transformed into inorganic fluoride ion after 4 h reaction. Shorter chain perfluorocarboxylic acids bearing C3-C7 and fluoride ion were detected and identified by LC/MS and IC as the degradation products in the aqueous solution. It was proposed that complexes of PFOA with Fe（Ⅲ） initiated degradation of PFOA irradiated with 254 nm UV light.     

AN INVESTIGATION ON THE INTERACTION MECHANISM OF β-CAROTENE WITH HALOGEN ATOM PRODUCED IN HALOBENZENE BY UV IRRADIATION

ESR measurements using spin trapping technique werecarried out for β-carotene-halobenzene system under UV lightirradiation.The ESR spectra observed in the presence andin the absence of β-carotene are markedly different.Thepossible scheme of β-carotene interacting with halogen atomwas proposed.