Structure of the green heme isolated from allylbenzene-modified chloroperoxidase: A novel heme architecture implicating the mechanisms of CPO inactivation and epoxidation.

The chemical identification of the modified heme (the green heme) during chloroperoxidase catalyzed epoxidation of allylbenzene remains unestablished due to its high instability within the protein matrix, the absence of paramagnetically shifted signals, and the difficulty in obtaining crystals of the modified enzyme. We have established the unambiguous structure of the modified prosthetic heme group, which was extracted from the protein matrix using 2D NMR spectroscopy and LC-MS spectrometry. The modified heme was isolated as a µ-oxo dimer that can be quantitatively converted to the corresponding monomer. The depolymerized green heme displayed characteristic NMR signatures of iron porphyrin complexes, but no Nuclear Overhauser Effect was observable to assist in signal assignment. An alternative strategy was applied by removing the iron center of the green heme, resulting in a stable demetallated green porphyrin species. Complete assignment of all the NMR resonances in the demetallated green heme allowed us to establish the molecular architecture of the modified species as a novel N-alkylated heme. Decisive space correlations between the propyl protons of allylbenzene and the γ meso proton coupled with clear dipolar connectivities between the propyl-2H of the substrate and the ß proton in the side chain of the propionic acid at carbon-6 of the porphyrin ring, clearly indicate that allylbenzene was covalently attached to the nitrogen atom of the pyrrole ring III of the prosthetic heme. In this study, the mechanism of green CPO formation and its relation to CPO catalyzed chiral transformations are also discussed. It is concluded that the double-phenyl clamp formed by two phenylalanine residues at the distal heme pocket plays a critical role in fine-tuning substrate orientation that determines the outcome of CPO catalyzed epoxidation of substituted styrenes.

Platinum(II) diimine complexes containing phenylpyridine ligands decorated with anionic closo-monocarborane clusters [CB11H12].

We report three Pt(II) diimine complexes containing ancillary ligands of phenylpyridine furnished with anionic closo-monocarborane clusters [CB11H12]-. Three neutral complexes exhibit intensive phosphorescence in the solid state and complex 1 was used to detect acetonitrile vapor in a quartz plate.

High strength, controlled release of curcumin-loaded ZIF-8/chitosan/zein film with excellence gas barrier and antibacterial activity for litchi preservation.

Polysaccharide films containing protein additives have good application prospects in agriculture and food field. However, interfacial incompatibility between hydrophobic proteins and hydrophilic polymers remains a major technical challenge. In this work, the interfacial compatibility between hydrophobic zein and hydrophilic chitosan (CS) is improved by the chemical crosslinking between zinc ions of curcumin-loaded zeolitic imidazolate framework-8 (Cur-ZIF-8) with CS and zein. With the improvement of interface compatibility, the results show that the elongation at break and O2 barrier property of synthesized Cur-ZIF-8/CS/Zein are 9.2 and 1.5 times higher than CS/Zein, respectively. And the Cur-ZIF-8/CS/Zein exhibits superior antibacterial and antioxidant properties as well. Importantly, Cur-ZIF-8/CS/Zein can also be used as an intelligent-responsive release platform for curcumin. As a result, Cur-ZIF-8/CS/Zein can keep the freshness and appearance of litchi at least 8 days longer than that of CS/Zein. Therefore, this study provides a novel method to improve the interfacial compatibility between hydrophobic proteins and hydrophilic polymers, and is expected to expand the application of protein/polymer composites in agriculture and food field.

Deep Blue Phosphorescence from Platinum Complexes Featuring Cyclometalated N-Pyridyl Carbazole Ligands with Monocarborane Clusters (CB11H12-).

The utilization of deep blue phosphorescent materials in high-performance displays and solid-state lighting requires high quantum efficiencies and color purities. Here, we describe the preparation and luminescent properties of novel platinum triplet emitters featuring cyclometalated N-pyridyl-carbazole ligands functionalized with closo-monocarborane clusters [CB11H12]-. All reported complexes were fully characterized by using standard small molecule techniques (UV-vis, cyclic voltammetry, nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS)), and their solid-state structures were elucidated by X-ray diffraction. These platinum phosphors emit in the blue region of the visible wavelength spectrum in both the solid and solution states. Complex 4a exhibits the highest luminous efficiency at λem = 439 nm with a photoluminescent quantum yield (PLQY) of 60% by dispersing in a PMMA matrix. Electrochemical and computational studies of complexes 4a and 4b revealed that the blue phosphorescence originates mainly from intraligand 3π → π* (3ILCT) transitions with relatively small 3MLCT mixing. A deep-blue OLED containing 4a as the light-emitting dopant was successfully fabricated using a solution-processed method, and the device exhibited blue photoluminescence with CIE coordinates of (0.17, 0.15) and a maximum external quantum efficiency (EQEmax) value of 6.2%. This article represents the pioneering study of a deep blue PhOLED using a Pt complex bearing a closo-monocarborane anion substituent, providing a new avenue into the preparation of novel triplet emitters based on boron-rich cluster anions.

Novel glycosylation zinc(II)-cryptolepine complexes perturb mitophagy pathways and trigger cancer cell apoptosis and autophagy in SK-OV-3/DDP cells.

With the aim of shedding some light on the mechanism of action of zinc(II) complexes in antiproliferative processes and molecular signaling pathways, three novel glycosylated zinc(II)-cryptolepine complexes, i.e., [Zn(QA1)Cl2] (Zn(QA1)), [Zn(QA2)Cl2] (Zn(QA2)), and [Zn(QA3)Cl2] (Zn(QA3)), were prepared by conjugating a glucose moiety with cryptolepine, followed by complexation of the resulting glycosylated cryptolepine compounds N-((1-(2-morpholinoethyl)-1H-1,2,3-triazol-4-yl)methyl)-benzofuro[3,2-b]quinolin-11-amine (QA1), 2-(4-((benzofuro[3,2-b]quinolin-11-ylamino)methyl)-1H-1,2,3-triazol-1-yl)ethan-1-ol (QA2), and (2S,3S,4R,5R,6S)-2-(4-((benzofuro[3,2-b]quinolin-11-ylamino)-methyl)-1H-1,2,3-triazol-1-yl)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (QA3) with zinc(II), and their anticancer activity was evaluated. In MTT assays, Zn(QA1)-Zn(QA3) were more active against cisplatin-resistant ovarian SK-OV-3/DDP cancer cells (SK-OV-3cis) than ZnCl2 and the QA1-QA3 ligands, with IC50 values of 1.81 ± 0.50, 2.92 ± 0.32, and 1.01 ± 0.11 µM, respectively. Complexation of glycosylated cryptolepine QA3 with zinc(II) increased the antiproliferative activity of the ligand, suggesting that Zn(QA3) could act as a chaperone to deliver the active ligand intracellularly, in contrast with other cryptolepine metal complexes previously reported. In vivo and in vitro investigations suggested that Zn(QA3) exhibited enhanced anticancer activity with treatment effects comparable to those of the clinical drug cisplatin. Furthermore, Zn(QA1)-Zn(QA3) triggered SK-OV-3cis cell apoptosis through mitophagy pathways in the order Zn(QA1) > Zn(QA1) > Zn(QA2). These results demonstrate the potential of glycosylated zinc(II)-cryptolepine complexes for the development of chemotherapy drugs against cisplatin-resistant SK-OV-3cis cells.

Green and multifunctional chitosan-based conformal coating as a controlled release platform for fruit preservation.

Food waste caused by the decay of perishable foods is a serious global issue. However, traditional preservative materials don't perform well in preventing food decay. Here, a green and multifunctional conformal coating is prepared by the hydrogen-bonding interactions among chitosan, nano-humic acid and curcumin, which is different from traditional preservative films obtained by solution blending. Thanks to the formation of hydrogen-bonding network, the surface roughness of the coating increased from 9.43 nm to 33.3 nm, which makes it more matches with the micro/nano structure of the fruit surface and obtains a good coating effect for various fruits. Furthermore, this coating shows distinctive mechanical properties (the tensile strength of 31.4 MPa), antioxidant and antibacterial activities (the inhibition zone ≥5 mm), and can be used to control the long-term release (up to 38 days) of natural preservative onto fruit surfaces. Through the demonstration of four perishable fruits, the coating can keep freshness and appearance at least 9 days longer than the uncoated samples, confirming the universal effectiveness of the coating in preventing fruit decay. This coating is easy to produce and use, washable, degradable, and makes from cheap or waste renewable biomaterials, which does not cause additional health and environmental concerns.

A triphenylphosphine coordinated cinnamaldehyde-derived copper(I) Fenton-like agent with mitochondrial aggregation damage for chemodynamic therapy.

Chemodynamic therapy (CDT), which uses agents to induce cell death by decomposing endogenous hydrogen peroxide (H2O2) into highly toxic hydroxyl radicals (˙OH), has been recognized as a promising approach to treat cancer. However, improving the efficiency of ˙OH production is considered one of the biggest challenges that limits the therapeutic efficacy of CDT. Herein, to controllably and efficiently induce oxidative damage through the production of ˙OH, we developed a new metal complex CDT agent with atomically precise structural characteristics as a deviation from traditional nanomaterial-CDT agents. The obtained CDT agent, a cinnamaldehyde derived copper(I) complex (denoted Cin-OD-Cu), was found to be continuously enriched in the mitochondria of A2780 ovarian carcinoma cells, which was accompanied by the generation of large amounts of ˙OH via Cu(I)-mediated Fenton-like reactions of H2O2, thereby stimulating oxidative stress in the mitochondria and eventually leading to cell death. Moreover, in vivo experiments showed that Cin-OD-Cu was capable of effectively inhibiting tumor growth with excellent biocompatibility. We believe this research enriches the limited selection of atomically precise metal complex CDT agents in particular for reactive oxygen species-mediated treatments aimed at inducing mitochondria oxidative damage; we anticipate that it will provide new insights into the development of novel, atomically precise agents for CDT.

Rational construction of a triphenylphosphine-modified tetra-nuclear Cu(I) coordinated cluster for enhanced chemodynamic therapy.

A triphenylphosphine-modified tetra-nuclear Cu(I) coordinated cluster was constructed for enhanced chemodynamic therapy (CDT) by increasing the number of metal centers. Once inside human bladder cancer (T24) cells, a larger amount of copper accumulated compared with the mono-nuclear Cu(I) complex; the additional copper could generate more •OH and then induce more obvious apoptosis via a Fenton-like reaction, thus further increasing the tumor inhibition effect and ultimately improving the CDT efficiency.

A simple and feasible atom-precise biotinylated Cu(i) complex for tumor-targeted chemodynamic therapy.

A simple and feasible atom-precise biotinylated Cu(i) complex, which can catalyze H2O2 overexpressed commonly in the tumor microenvironment to produce ˙OH through a Fenton-like reaction, was prepared and employed as an effective agent for tumor-targeted chemodynamic therapy.

Constructing an unprecedented {MnII38} matryoshka doll with a [Mn18(CO3)9] inorganic core and magnetocaloric effect.

An unprecedented inner [Mn18(CO3)9] inorganic core and [Mn20] metal-organic periphery compose a high-nuclearity homometallic single-valent {MnII38} molecular aggregate with a [Mn6] ⊂ [Mn12] ⊂ [Mn8] ⊂ [Mn12] matryoshka doll-like skeleton that displays a significant magnetocaloric effect (MCE).

Hierarchical Construction and Magnetic Difference of {Co12M12} (M = Co2+/Cd2+) Aggregates from {Co14} Cluster-Based Precursors in the Presence of Homo/Heterometal Salts.

The controllable construction and function expansion of some sophisticated aggregations represent a current hot topic in scientific research. In this paper, using a prefabricated {Co14} cluster as a synthetic precursor, a homometallic {Co24} and a heterometallic {Co12Cd12} giant cluster possessing similar dual-[M12] (M = Co/Cd) skeletons was prepared by reacting the precursor with excess CoCl2 and Cd(OAc)2 salts, respectively. The detailed structural information on {Co24} and {Co12Cd12} was characterized by single-crystal X-ray diffraction and further analyzed by X-ray photoelectron spectroscopy, inductively coupled plasma-mass spectroscopy, and scanning electron microscopy with energy dispersive X-ray (EDX) spectroscopy in the solid state. Compared to the {Co14} precursor, magnetic difference revealed that spin-canting and magnetic ordering had been enhanced in {Co24} and suppressed in {Co12Cd12} when dotted with diamagnetic Cd2+ ions.

A novel sandwich shaped {CoCoMo} cluster with a Co triangle encapsulated in two capped CoIIICoMoO40 fragments.

A novel discrete {Co14Mo24} nanoscale cluster, {CoIII2CoII10Cl2(dpbt)3(H2O)2[CoIIMoV12O31(CH3O)9]2}·24CH3OH (1) (here, dpbt = 5,5'-di(pyridin-2-yl)-3,3'-bi(1,2,4-triazole)), with a triangular Co4 core encapsulated in two novel capped Co-substituted Keggin-type Co5Mo12O40 anions, has been isolated from alkaline methanol solution. The high-resolution electrospray ionization mass spectrum (HRESI-MS) of microcrystalline 1 in MeOH/CH2Cl2 (v : v = 2 : 1) was recorded. Two prominent overlapping peaks in the range of m/z = 2740-2840 and 1820-1880 for the discrete fragments of [CoIII2CoII12MoV24O62Cl2(dpbt)3(H2O)2(CH3O)x(OH)18-x-2H]2- (x = 9-18, F1) and [CoIII2CoII12MoV24O62Cl2(dpbt)3(H2O)2(CH3O)x(OH)19-x-2H]3- (x = 6-13, F2), respectively, are obtained, confirming the {Co14Mo24} composition in 1. In addition, weak anti-ferromagnetic interactions in 1 are observed.

Two groups of copperII pyridine-triazole complexes with "open or close" pepper rings and their in vitro antitumor activities.

Based on 1,2-dimethoxyphenyl (veratrole, open) and 1,2-methylenedioxyphenyl (pepper ring, close)-derived pyridine-triazole analogues, two groups of copper(ii) complexes, namely, Group I(C1-C3) and Group II(C4-C6) were synthesized and fully characterized. All ligands and complexes were tested in vitro by MTT assays on seven tumour cell lines (T24, Hep-G2, Sk-Ov-3, MGC-803, HeLa, A549 and NCI-H460) and one normal liver cell line (HL-7702). Surprisingly, the pepper-ring-derived complexes (C4-C6) showed significantly enhanced cytotoxicity compared with the 1,2-bimethoxyphenyl ring-derived complexes (C1-C3) and the standard anticancer drug cisplatin. Cellular uptake assays indicated that the Cu accumulation was consistent with cytotoxicity. In addition, flow cytometry and western blot analysis showed that the apoptosis of the leading complex C4 may be induced by the Bcl-2 family-mediated proteins through the mitochondrial dysfunction pathway. Furthermore, UV-vis and fluorescence spectroscopy assays revealed that C4 has stronger insertion-binding interactions with CT-DNA than C1 and the fluorescence of C1 and C4 with BSA is mainly quenched by static quenching.

In Situ Metal-Ligand Reactions under Solvent-Dependent Hydro(solvo)thermal Conditions: Structures, Mass Spectrometry, and Magnetism.

In this study, four in situ hydro(solvo)thermal metal-ligand reactions, including oxidation (H2L1), C-C coupling (H4L2), nitration (H2L3), and condensation (HL4-6), based on bis[3-(pyridin-2-yl)-1H-1,2,4-triazol-5-yl]methane (H2L0), in the presence of DyIII ions, were carried out. The in situ metal-ligand reaction gave six new ligands existing in eight novel DyIII coordination complexes, which were characterized by crystal structure, mass spectrometry, and magnetism.

Hierarchical Assembly of a {Co24} Cluster from Two Vertex-Fused {Co13} Clusters and Their Single-Molecule Magnetism.

We present the synthesis, structural characterization, and magnetic properties of two high-nuclearity cobalt clusters formulated as [Co13(µ3-OH)3(µ3-Cl)(dpbt)5(ptd)Cl10][Co(H2O)2Cl2]·(CH3)2CHOH (1) and [Co24(µ3-OH)6(µ3-Cl)2(dpbt)10(ptd)2Cl16]·2CH3CH2OH (2), respectively (H2dpbt = 5,5'-bis(pyridin-2-yl)-3,3'-bis(1,2,4-triazole) and H2ptd = 3-(pyridin-2-yl)-1,2,4-triazine-5,6-diol). Compound 1 is composed of an inner [Co4(µ3-OH)3(µ3-Cl)] cubane and an outer [Co9(dpbt)5(ptd)Cl10] defective adamantane. Compound 2 reveals a giant {Co24} cluster possessing a dual-[Co12] skeleton from 1. The hierarchical assembly from 1 to 2 has been established and tracked through high-resolution electrospray ionization (HRESI-MS) analyses from the solvothermal reaction mother solution. Magnetic studies of 1 and 2 revealed the highly correlated spins, a glasslike magnetic phase transition at ca. 8 K, and slow relaxation behavior of SMM nature in the lower-temperature region (below 4 K).

Schiff base complex conjugates of bovine serum albumin as artificial metalloenzymes for eco-friendly enantioselective sulfoxidation.

Artificial metalloenzymes (BSA-ML) have been prepared by non-covalent insertion of transition metal Schiff-base complexes, ML (L = 2-hydroxynaphthalen-1-naphthaldehyde and 3,4-diaminobenzenesulfonic acid; M = Co, Mn, V, Fe, Cr), into bovine serum albumin (BSA) as the host protein and were characterized by UV-visible spectroscopy, ESI-TOF mass spectrometry and molecular docking studies. The catalytic activities of the BSA-ML in the selective oxidation of various prochiral sulfides in aqueous media, using H2O2 as oxidant, have been evaluated. During the optimization process, pH and the concentrations of catalyst and oxidant were found to have a remarkable influence on both yield and enantioselectivity. In certain cases, BSA-ML gave satisfactory results in the oxidation of organic sulfides to sulfoxides (up to 100% conversion, 100% chemoselectivity, 96% ee and 500 h-1 turnover frequency).

Ni(II) Complexes with Schiff Base Ligands: Preparation, Characterization, DNA/Protein Interaction and Cytotoxicity Studies.

In this study, two Ni(II) complexes, namely [Ni(HL1)2(OAc)2] (1) and [Ni(L2)2] (2) (where HL1 and HL2 are (E)-1-((1-(2-hydroxyethyl)-1H-pyrazol-5-ylimino)methyl)-naphthalen-2-ol) and (E)-ethyl-5-((2-hydroxynaphthalen-1-yl)methyleneamino)-1-methyl-1H-pyrazole-4-carboxylate, respectively), were synthesized and characterized by X-ray crystallography, Electrospray Ionization Mass Spectrometry (ESI-MS), elemental analysis, and IR. Their uptake in biological macromolecules and cancer cells were preliminarily investigated through electronic absorption (UV-Vis), circular dichroism (CD) and fluorescence quenching measurements. Bovine serum albumin (BSA) interaction experiments were investigated by spectroscopy which showed that the complexes and ligands could quench the intrinsic fluorescence of BSA through an obvious static quenching process. The spectroscopic studies indicated that these complexes could bind to DNA via groove, non-covalent, and electrostatic interactions. Furthermore, in vitro methyl thiazolyl tetrazolium (MTT) assays and Annexin V/PI flow cytometry experiments were performed to assess the antitumor capacity of the complexes against eight cell lines. The results show that both of the complexes possess reasonable cytotoxicities.

Bovine serum albumin-cobalt(ii) Schiff base complex hybrid: an efficient artificial metalloenzyme for enantioselective sulfoxidation using hydrogen peroxide.

An artificial metalloenzyme (BSA-CoL) based on the incorporation of a cobalt(ii) Schiff base complex {CoL, H2L = 2,2'-[(1,2-ethanediyl)bis(nitrilopropylidyne)]bisphenol} with bovine serum albumin (BSA) has been synthesized and characterized. Attention is focused on the catalytic activity of this artificial metalloenzyme for enantioselective oxidation of a variety of sulfides with H2O2. The influences of parameters such as pH, temperature, and the concentration of catalyst and oxidant on thioanisole as a model are investigated. Under optimum conditions, BSA-CoL as a hybrid biocatalyst is efficient for the enantioselective oxidation of a series of sulfides, producing the corresponding sulfoxides with excellent conversion (up to 100%), chemoselectivity (up to 100%) and good enantiomeric purity (up to 87% ee) in certain cases.

Synthesis, characterization, DNA/protein interaction and cytotoxicity studies of Cu(II) and Co(II) complexes derived from dipyridyl triazole ligands.

Four different transition metal complexes containing dipyridyl triazole ligands, namely [Cu(abpt)2Cl2]·2H2O (1), [Cu(abpt)2(ClO4)2] (2), [Co2(abpt)2(H2O)2Cl2]·Cl2·4H2O (3) and [Co2(Hbpt)2(CH3OH)2(NO3)2] (4) have been designed, synthesized and further structurally characterized by X-ray crystallography, ESI-MS, elemental analysis, IR and Raman spectroscopy. In these complexes, the both ligands act as bidentate ligands with N, N donors. DNA binding interactions with calf thymus DNA (ct-DNA) of the ligand and its complexes 1~4 were investigated via electronic absorption, fluorescence quenching, circular dichroism and viscosity measurements as well as confocal Laser Raman spectroscopy. The results show these complexes are able to bind to DNA via the non-covalent mode i.e. intercalation and groove binding or electrostatic interactions. The interactions with bovine serum albumin (BSA) were also studied using UV-Vis and fluorescence spectroscopic methods which indicated that fluorescence quenching of BSA by these compounds was the presence of both static and dynamic quenching. Moreover, the in vitro cytotoxic effects of the complexes against four cell lines SK-OV-3, HL-7702, BEL7404 and NCI-H460 showed the necessity of the coordination action on the biological properties on the respective complex and that all four complexes exhibited substantial cytotoxic activity.

An intuitional hierarchical assembly of cluster-organic frameworks with a thickness of 1.97 nm from a discrete Co14 cluster.

An intuitional hierarchical assembly, metaphorically referred to as a "blossom and yield fruit" process, from a discrete cluster {[Co14(CH3O)4(dpbt)6Cl12]·14CH3OH, ()} to 2D cluster organic frameworks {[Co14(CH3O)10(dpbt)6 Cl6]·12CH3OH, ()}, has been established. The magnetic ordering of was obviously improved compared with .