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Antimony (Sb) is currently a widespread element with key roles in telecommunication, sustainable energy, and military industries, among others. Its significant toxicity determines the need to realize sensors for water, air, and soil and the industrial process monitoring of Sb species. Unfortunately, no antimony sensors exist so far, and just laboratory analysis methods are in use. We aimed to contribute to the development of optical sensors for the metalloid by tailoring, for the first time, luminescent Ru(II) and Re(I) polypyridyl complexes to probe and quantify the presence of Sb(III). The molecular design of the complexes includes the multifunctional Sb-binding 2-(2,2′-bithien-5-yl)-1H-imidazo[4,5-f]-1,10-phenanthroline (btip) ligand that ensures the molecular binding of Sb(III) in organic media. The Ru(II)-btip complex is additionally endowed with one 2,2′-bipyrazine (bpz) or two 1,4,5,8-tetraazaphenanthrene (tap) ligands, namely [Ru(bpz)(btip)2]2+ and [Ru(tap)2(btip)]2+, that boost the excited state oxidation potential of the probe, leading to an intramolecular photoinduced electron transfer from btip to the Ru(II) core. The latter is suppressed upon interaction with Sb(III), leading to an 11-fold increase in both the luminescence intensity and lifetime of [Ru(bpz)(btip)2]2+ in the presence of ca. 50 μmol L−1 of SbCl3 in organic medium. The fluorescence intensity of [Re(CO)3(H2O)(btip)]+ also increases upon interaction with Sb(III) but to a much lesser extent due to the intraligand π*→π nature of its emission compared to the Ru(II) ligand-to-metal excited state deactivation. However, the weak π*→d emission band in the red spectral region of the former is quenched by the semimetallic element. The sensing mechanisms of the Ru(II)- and Re(I)-btip probes that allow luminescence intensity (Ru, Re), ratiometric (Ru), and lifetime measurements (Ru) are compared and discussed in this initial solution sensing study. [ABSTRACT FROM AUTHOR]

Antimony (Sb) is currently a widespread element with key roles in telecommunication, sustainable energy, and military industries, among others. Its significant toxicity determines the need to realize sensors for water, air, and soil and the industrial process monitoring of Sb species. Unfortunately, no antimony sensors exist so far, and just laboratory analysis methods are in use. We aimed to contribute to the development of optical sensors for the metalloid by tailoring, for the first time, luminescent Ru(II) and Re(I) polypyridyl complexes to probe and quantify the presence of Sb(III). The molecular design of the complexes includes the multifunctional Sb-binding 2-(2,2′-bithien-5-yl)-1H-imidazo[4,5-f]-1,10-phenanthroline (btip) ligand that ensures the molecular binding of Sb(III) in organic media. The Ru(II)-btip complex is additionally endowed with one 2,2′-bipyrazine (bpz) or two 1,4,5,8-tetraazaphenanthrene (tap) ligands, namely [Ru(bpz)(btip)2]2+ and [Ru(tap)2(btip)]2+, that boost the excited state oxidation potential of the probe, leading to an intramolecular photoinduced electron transfer from btip to the Ru(II) core. The latter is suppressed upon interaction with Sb(III), leading to an 11-fold increase in both the luminescence intensity and lifetime of [Ru(bpz)(btip)2]2+ in the presence of ca. 50 μmol L−1 of SbCl3 in organic medium. The fluorescence intensity of [Re(CO)3(H2O)(btip)]+ also increases upon interaction with Sb(III) but to a much lesser extent due to the intraligand π*→π nature of its emission compared to the Ru(II) ligand-to-metal excited state deactivation. However, the weak π*→d emission band in the red spectral region of the former is quenched by the semimetallic element. The sensing mechanisms of the Ru(II)- and Re(I)-btip probes that allow luminescence intensity (Ru, Re), ratiometric (Ru), and lifetime measurements (Ru) are compared and discussed in this initial solution sensing study.

Daminozide, a plant growth regulator, is an effective inhibitor of the Jumonji domain-containing protein (JMJD) histone demethylase. Herein, four ruthenium(II)/rhenium(I)-daminozide conjugates, with molecular formulas [Ru(N-N)2bpy(4-CH2OH-4′-CH2O-daminozide)](PF6)2 (Ru-1/Ru-2) (N-N = 1,10-phenanthroline (phen, in Ru-1) and 4,7-diphenyl-1,10-phenanthroline (DIP, in Ru-2)) and Re(N-N)(CO)3(PyCH2O-daminozide) (Re-1/Re-2) (Py = pyridine, N-N = phen (in Re-1) and DIP (in Re-2)), were synthesized and characterized. Among these complexes, Ru-2 and Re-2 exhibited higher cytotoxicity against tumor cells than cisplatin. Upregulation of H3K9Me3 expression level was found in human cervical cancer cells (HeLa) treated with Ru-2 and Re-2, indicating that these two complexes can inhibit the activity of JMJD histone demethylase. Further investigation revealed that Re-2 can selectively accumulate in the mitochondria of HeLa cells. Both Ru-2 and Re-2 can cause mitochondrial damage, induce apoptosis, and inhibit cell migration and colony formation of HeLa cells. Overall, these complexes exhibit multiple anticancer functions, including inhibiting JMJD, inducing apoptosis, and inhibiting cell invasion, making them promising candidates for anticancer drugs. [ABSTRACT FROM AUTHOR]

Two new rhenium(I) porphyriniod complexes (H2PY: 3,3-rhenium(I) tricarbonyl chloride-(31E,32Z,71E,72Z)-4,8-bis(perfluorophenyl)-11H,32H,72H-51λ2,71λ4-1,5(2,5),3,7(5,2)-tetrapyrrola-2,6(1,2)-dibenzenacyclooctaphane, and H2PZ: 3,3-rhenium(I) tricarbonyl acetate-(31E,32Z,71E,72Z)-4,8-bis(perfluorophenyl)-11H,32H,72H-51λ2,71λ4-1,5(2,5),3,7(5,2)-tetrapyrrola-2,6(1,2)-dibenzenacyclooctaphane) containing two different Re(I)−N π-bonding networks were prepared from the saddle-shaped porphyrin(2.1.2.1) bearing pentafluorophenyl substituents at the two meso-positions (H2Por: 31E,32Z,71E,72Z)-4,8-bis(perfluorophenyl)-11H,32H,51H,72H-1,5(2,5),3,7(5,2)-tetrapyrrola-2,6(1,2)-dibenzenacyclooctaphane). Despite the tetrapyrrolic nature of the porphyrin(2.1.2.1) scaffold, this is the first case of a pyrrole-based macrocycle which acts as a bipyridyl-like complexing ligand in the formation of an octahedral Re(I) complex. X-ray analysis and 1H NMR studies show that both Re(I) complexes (H2PY and H2PZ) consist of one octahedral Re(I) ion π-bonded to a dipyrrin unit and one protonated dipyrrin moiety linked together through o-phenylene bridges. This bonding behavior is compared to related metal complexes of porphyrin(2.1.2.1) macrocycles as well as other Re(I) porphyrins and demonstrates that the distorted conformation and, by virtue, the electronics of H2Por serve as a novel platform for examining structure property relationships which differ than those of other related planar porphyrin macrocycles. [ABSTRACT FROM AUTHOR]

Daminozide, a plant growth regulator, is an effective inhibitor of the Jumonji domain-containing protein (JMJD) histone demethylase. Herein, four ruthenium(II)/rhenium(I)-daminozide conjugates, with molecular formulas [Ru(N-N)2bpy(4-CH2OH-4′-CH2O-daminozide)](PF6)2 (Ru-1/Ru-2) (N-N = 1,10-phenanthroline (phen, in Ru-1) and 4,7-diphenyl-1,10-phenanthroline (DIP, in Ru-2)) and Re(N-N)(CO)3(PyCH2O-daminozide) (Re-1/Re-2) (Py = pyridine, N-N = phen (in Re-1) and DIP (in Re-2)), were synthesized and characterized. Among these complexes, Ru-2 and Re-2 exhibited higher cytotoxicity against tumor cells than cisplatin. Upregulation of H3K9Me3 expression level was found in human cervical cancer cells (HeLa) treated with Ru-2 and Re-2, indicating that these two complexes can inhibit the activity of JMJD histone demethylase. Further investigation revealed that Re-2 can selectively accumulate in the mitochondria of HeLa cells. Both Ru-2 and Re-2 can cause mitochondrial damage, induce apoptosis, and inhibit cell migration and colony formation of HeLa cells. Overall, these complexes exhibit multiple anticancer functions, including inhibiting JMJD, inducing apoptosis, and inhibiting cell invasion, making them promising candidates for anticancer drugs.

The hypoxic microenvironment of solid tumors severely lowers the efficacy of oxygen-dependent photodynamic therapy (PDT). The development of hypoxia-tolerant photosensitizers for PDT is an urgent requirement. In this study, a novel rhenium complex (Re-TTPY) to develop a "closed-loop" therapy based on PDT-induced ferroptosis and immune therapy is reported. Due to its electron donor-acceptor (D-A) structure, Re-TTPY undergoes energy transfer and electron transfer processes under 550 nm light irradiation and displays hypoxia-tolerant type I/II combined PDT capability, which can generate 1 O 2 , O 2 - , and ·OH simultaneously. Further, the reactive oxygen species (ROSs) leads to the depletion of 1,4-dihydronicotinamide adenine dinucleotide (NADH), glutathione peroxidase 4 (GPX4), and glutathione (GSH). As a result, ferroptosis occurs in cells, simultaneously triggers immunogenic cell death (ICD), and promotes the maturation of dendritic cells (DCs) and infiltration of T cells. The release of interferon-γ (IFN-γ) by CD8+ T cells downregulates the expression of GPX4, further enhancing the occurrence of ferroptosis, and thereby, forming a mutually reinforcing "closed-loop" therapeutic approach., (© 2024 Wiley‐VCH GmbH.)

The photocatalytic reduction of CO2 into fuels offers the prospect for creating a new CO2 economy. Harnessing visible light‐driven CO2‐to‐CO reduction mediated by the long‐lived triplet excited state of rhenium(I) tricarbonyl complexes is a challenging approach. We here develop a series of new mononuclear rhenium(I) tricarbonyl complexes (Re‐1−Re‐4) based on the imidazole‐pyridine skeleton for photo‐driven CO2 reduction. These catalysts are featured by combining pyridyl‐imidazole with the aromatic ring and different pendant organic groups onto the N1 position of 1,3‐imidazole unit, which display phosphorescence under Ar‐saturated solution even at ambient conditions. By contrast, {Re[9‐(pyren‐1‐yl)‐10‐(pyridin‐2‐yl)‐9H‐pyreno[4,5‐d]imidazole)](CO)3Cl} (Re‐4) by introducing pyrene ring at the N1 position of pyrene‐fused imidazole unit exhibits superior catalytic performance with a higher turnover number for CO (TONCO=124) and >99.9 % selectivity, primarily ascribed to the strong visible light‐harvesting ability, long‐lived triplet lifetimes (164.2 μs) and large reductive quenching constant. Moreover, the rhenium(I) tricarbonyl complexes derived from π‐extended pyrene chromophore exhibit a long lifetime corresponding to its ligand‐localized triplet state (3IL) evidenced from spectroscopic investigations and DFT calculations. [ABSTRACT FROM AUTHOR]

In this work, two classes of Carbonic Anhydrase (CA) inhibitors, sulfonamide and coumarin derivatives linked to pyta moiety (2a-b) and their corresponding rhenium complexes (3a-b), were designed. These compounds were synthesized and fully characterized by classical analytical methods and X-ray diffraction. All the synthesized compounds were evaluated for their inhibitory activity against the hCA isoforms I, II, IX and XII. They exhibited high inhibitory activities in the range of nanomolar for both hCA IX and hCA XII isoforms. The sulfonamide compound 2a showed the strongest inhibition against the tumour-associated hCA IX isoform with a Ki of 11.7 nM. The tumour-associated isoforms hCA IX and hCA XII were selectively inhibited by all the coumarin derivatives, with inhibition constants ranging from 12.7 nM (2b) to 44.5 nM (3b), while the hCA I and II isoforms were slightly inhibited (in the micromolar range), as expected. In terms of selectivity, compared to previously published rhenium complex-based CA inhibitors, complex 3b showed one of the highest selectivities against hCA IX and hCA XII compared to the off-target isoforms hCA I and hCA II, making it a potential anti-cancer drug candidate. Molecular docking calculations were performed to investigate the inhibition profiles of the investigated compounds at the tumour-associated hCA IX active site and to rationalize our results.

Abstract Synthesis of the four rhenium(I) diimine surfactant complexes of the type fac- [Re(CO) 3 (α-diimine){4-C 11 py}] CF 3 SO 3 1a-1d (α-diimine = 2,2′-bipyridine (a), 4,4′-di-methyl-2,2′-bipyridine (b), 4,4′-di- tert -butyl-2,2′-bipyridine (c) 4,4′-dinonyl-2,2′-bipyridine (d) and 4-C 11 py = (py-4-(CH 2) 10 CH 3) has been reported. In vitro protein (HSA and BSA) binding studies confirmed the binding affinity of the complexes toward the drug binding sites of subdomain IIA and IIIA , confirmed by spectral studies and molecular docking. The steady-state and time-resolved fluorescence spectra confirm that the static quenching, due to complex formation, is the dominant mechanism for fluorescence quenching. Molecular docking studies prove that hydrophobic interaction makes a predominant contribution even though hydrogen bonding does exist, and hence 1b, 1c and 1d exhibit stronger binding relative to 1a. The synchronous fluorescence and circular dichroism spectral studies show that these Re(I) complexes can induce conformational changes in the proteins. Finally, the distance, r, between donor (proteins) and acceptor (Re (I) complexes) obtained through FRET study is in the range 4.5–5.2 nm. [ABSTRACT FROM AUTHOR]

The search for new metal-based photosensitizers (PSs) for anticancer photodynamic therapy (PDT) is a fast-developing field of research. Knowing that polymetallic complexes bear a high potential as PDT PSs, in this study, we aimed at combining the known photophysical properties of a rhenium(I) tricarbonyl complex and a ruthenium(II) polypyridyl complex to prepare a ruthenium-rhenium binuclear complex that could act as a PS for anticancer PDT. Herein, we present the synthesis and characterization of such a system and discuss its stability in aqueous solution. In addition, one of our complexes prepared, which localized in mitochondria, was found to have some degree of selectivity towards two types of cancerous cells: human lung carcinoma A549 and human colon colorectal adenocarcinoma HT29, with interesting photo-index (PI) values of 135.1 and 256.4, respectively, compared to noncancerous retinal pigment epithelium RPE1 cells (22.4)., (© 2023 The Authors. ChemBioChem published by Wiley-VCH GmbH.)

A new bridging ligand has been prepared in which two chelating bidentate pyrazolyl-pyridine termini are connected to a central naphthalene-2,7-diyl core via methylene spacer units. This ligand has been used to prepared mononuclear and dinuclear Ir(III) complexes in which {Ir(F 2 ppy) 2 } [F 2 ppy = cyclometallating anion of 2-(3,5-difluorophenyl)-pyridine] complex fragments are coordinated to one or both of the pyrazolyl-pyridine termini; in addition a heterodinuclear complex has been prepared containing one {Ir(F 2 ppy) 2 } unit and one {Re(CO) 3 Cl} unit in the two binding sites. X-ray crystallographic studies show that the bridging naphthyl group lies stacked with a coordinated F 2 ppy ligand from a terminal {Ir(F 2 ppy) 2 } unit in every case. Luminescence measurements show that the usual strong Ir(III)-centred blue luminescence is substantially quenched by the presence of a low-lying triplet state on the naphthyl group; in the Ir(III)/Re(I) dyad we observe both weak Ir(III)-based emission as well as lower-energy Re(I)-based emission which overlap; Ir(III) → Re(I) energy-transfer occurs on a timescale of <1 ns as no rise-time for sensitised Re(I)-based emission could be detected, in contrast to other Ir(III)/Re(I) dyads in which the Ir(III) → Re(I) energy-transfer is slower (10–100 ns timescale). We ascribe this to the spatial and energetic intermediacy of the naphthyl group whose triplet energy lies between that of the Ir(III) and Re(I) termini, providing an effective conduit for energy-transfer to occur. [ABSTRACT FROM AUTHOR]

A new synthetic route to acquire the water soluble complex fac-Re(CO)(pterin)(HO) was carried out in aqueous solution. The complex has been obtained with success via the fac-[Re(CO)(HO)]Cl precursor complex. Re(CO)(pterin)(HO) has been found to bind strongly with bovine and human serum albumins (BSA and HSA) with intrinsic-binding constants, K, of 6.5 × 10 M and 5.6 × 10 M at 310 K, respectively. The interactions of serum albumins with Re(CO)(pterin)(HO) were evaluated employing UV-vis fluorescence and absorption spectroscopy and circular dichroism. The results suggest that the serum albumins-Re(CO)(pterin)(HO) interactions occurred in the domain IIA-binding pocket without loss of helical stability of the proteins. The comparison of the fluorescence quenching of BSA and HSA due to the binding to the Re(I) complex suggested that local interaction around the Trp 214 residue had taken place. The analysis of the thermodynamic parameters ΔG, ΔH, and ΔS indicated that the hydrophobic interactions played a major role in both HSA-Re(I) and BSA-Re(I) association processes. All these experimental results suggest that these proteins can be considered as good carriers for transportation of Re(CO)(pterin)(HO) complex. This is of significant importance in relation to the use of this Re(I) complex in several biomedical fields, such as photodynamic therapy and radiopharmacy. [ABSTRACT FROM AUTHOR]

A mononuclear Re(I) complex, [ReCl(CO) 3 (phen-dione)], was investigated as a new electrocatalyst for the reduction of CO 2 in two catalytic systems (homogeneous and heterogeneous) by voltammetry experiments. A modified pencil graphite electrode with carboxylated multiwall carbon nanotubes (CMWCNTs-PGE) was used as a working electrode for both catalytic systems. In the homogeneous system, the Re(I) complex revealed the catalytic activity for the reduction of CO 2 to CO in an acetonitrile solution at the onset potential of −545 mV vs. NHE. Also, the results showed that the presence of methanol as a weak Bronsted acid enhanced the rate of the catalytic process for the reduction of CO 2 in the homogenous condition. In the heterogonous condition, the Re(I) complex was simply casted on the CMWCNTs-PGE and then investigated for the reduction of CO 2 in an acidic solution of MeOH. The results also revealed that the onset potential for the heterogeneous catalyst was more positive than the homogenous condition. Also, the cathodic current density for the heterogeneous catalyst was higher in an acidic solution of MeOH. Adding sulfuric acid shifted the onset potential about 477 mV toward the more positive potential (at the onset potential of −390 mV vs. NHE) and increased the cathodic current about 10.7 times in the heterogeneous reduction of CO 2 . [ABSTRACT FROM AUTHOR]

A series of alkynylrhenium(I) tricarbonyl diimine complexes with fused thiophene and cyanoacrylic acid moiety has been synthesized and characterized. A long-lived charge separated state of these complexes have been found. Preliminary studies to explore the utilization of these complexes as photosensitizers have also been made, which show photoresponse upon light illumination. [ABSTRACT FROM AUTHOR]

We have described herein a series of unsymmetric 1,10-phenanthroline (phen) based aromatic heterocyclic derivatives with triphenylamine (TPA) and thiophene donors ( L1 – L5 ) and their respective neutral tricarbonyl rhenium(I) complexes ( 6a – 6e ). Comparisons between isomeric compounds L1 / L2 and 6a / 6b as well as L3 / L4 / L5 and 6c / 6d / 6e have been made on their 1 H NMR and UV/Vis spectra, single-crystal structures and density function theory (DFT) calculations. The alterations of conjugated system of the whole molecules, originating from the introduction of 2-, 3- or 3,8-substituted TPA and thiophene groups of phen, are responsible for the structural and spectral discrepancy of these structural isomers. In particular, the introduction of TPA and/or thiophene donors at 2-postion of phen ( L1 and L3 ) leads to smaller band gaps than their respective 3-substituted isomers ( L2 and L4 ). In addition, rhenium(I) ion complexation could slightly lower the highest occupied molecular orbital (HOMO) energy levels but significantly decrease the lowest unoccupied molecular orbital (LUMO) energy levels of the molecular system. [ABSTRACT FROM AUTHOR]

A novel tricarbonyl rhenium(I) coordination compound of 5-amine-1,10-phenanthroline has been synthesized and fully characterized by IR, NMR ( 1 H and 13 C), UV–vis spectroscopy and single crystal X-ray analysis. The luminescent properties of [ReCl(CO) 3 (NH 2 -phen)] were studied in solution at 298 and 77 K and compared with the free ligand. To get detailed insight into the electronic structure and spectroscopic properties of [ReCl(CO) 3 (NH 2 -phen)], the density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed. [ABSTRACT FROM AUTHOR]

Abstract: A rhenium(I) complex ReL R,R (CO)3Cl (1) based on a chiral ligand, L R,R =(−)-4,5-pinene-2,2′-bipyridine [(6R)-5,6,7,8-tetrohedro-7,7-dimethyl-3-(2-pyridinyl)-6,8-methanoisoquinoline], was synthesized and characterized. The emission spectrum of 1 shows efficient dπ(Re)→π* (diimine) (MLCT) phosphorescence with a photoluminescence quantum efficiency of 0.035. The excited state lifetimes of Re(I) complex, measured in CH2Cl2 solution (1.82μs) and solid state (2.15μs) at room temperature, support the hypothesis of the MLCT character of the emitting state. Single crystal X-ray diffraction analyses show that complex 1 crystallizes in the chiral space group P21 of monoclinic system. The P–E hysteresis loop indicates its obvious ferroelectricity with the remnant polarization (P r) value of 0.17μC/cm2 at an applied field of 4.8kV/cm. To the best of our knowledge, complex 1 represents the first rhenium-based complex reported with ferroelectricity. [Copyright &y& Elsevier]

Four rhenium(I) complexes Rel.l ReL4 based on dipyrido[3,2-a:2',3'-c]phenazine (LI) and derivatives L2-L4 ligands (L2: 10,13-dibromodipyrido[3,2-a:2',3'-c]phenazine, L3: 10-bromo-13-carbazolyl-dipyrido[3,2-a:2',3'-c]phenazine, L4: 10,13-dicarbazolyldipyrido[3,2-a:2',3'-c]phenazine) were synthesized and characterized. The Re(I) complexes ReLl ReL4 show photoluminescent emissions at 556, 582, 637 and 662 nm, respectively, assigned to dn (Re)-->π* (diimine) MLCT phosphorescence in CH2CI2 solution. The carbazole containing complexes ReL3 and ReL4, as com-pared to ReLl, exhibit higher luminescence. These observations imply that modification of diimine rhenium(l) carbonyl complexes with carbazole moiety would lead to efficient phosphorescent properties. [ABSTRACT FROM AUTHOR]

Cholesterol is vital to control membrane integrity and fluidity, but is also a precursor to produce steroid hormones, bile acids, and vitamin D. Consequently, altered cholesterol biology has been linked to many diseases, including metabolic syndromes and cancer. Defining the intracellular pools of cholesterol and its trafficking within cells is essential to understand both normal cell physiology and mechanisms of pathogenesis. We have synthesized a new cholesterol mimic (ReTEGCholestanol), comprising a luminescent rhenium metal complex and a cholestanol targeting unit, linked using a tetraethylene glycol (TEG) spacer. ReTEGCholestanol demonstrated favourable imaging properties and improved water solubility when compared to a cholesterol derivative, and structurally related probes lacking the TEG linker. A non-malignant and three malignant prostate cell lines were used to characterize the uptake and intracellular distribution of ReTEGCholestanol. The ReTEGCholestanol complex was effectively internalized and mainly localized to late endosomes/lysosomes in non-malignant PNT1a cells, while in prostate cancer cells it also accumulated in early endosomes and multivesicular bodies, suggesting disturbed cholesterol biology in the malignant cells. The ReTEGCholestanol is a novel imaging agent for visualizing endosomal uptake and trafficking, which may be used to define cholesterol related biology including membrane integration and altered lipid trafficking/processing., (© The Author(s) 2022. Published by Oxford University Press.)

Abstract: The ground and excited state geometries and frontier molecular orbital, absorption and emission properties of the four transition metal complexes Re(bpy)(CO)3(PEt3)+ (1), Re(bpy)(CO)3(PPh3)+ (2), Re(bpy)(CO)3[P(OEt3)]+ (3) and Re(bpy)(CO)3[P(OPh3)]+ (4) were studied theoretically. The introduction of different phosphine ligands significantly changed the geometric parameters of the complexes. The axial Re–C bond distance was longer than the equatorial Re–C bond distance. The lowest lying absorption bands of 1 and 2 have HOMO→LUMO transition configurations resulting in MLCT/LLCT transition characteristics. The HOMO-1→LUMO transition predominantly contributed to the lowest absorption bands of 3 with MLCT/LLCT characteristics. The absorption band of 4 at 326nm was dominated by HOMO-4→LUMO and HOMO-6→LUMO transitions with mixed MLCT/LLCT characteristics. The phosphorescence emission energies of 1–4 were also calculated and compared with the experimental values. [ABSTRACT FROM AUTHOR]

Abstract: Two new rhenium(I) carbonyl complexes with cationic 2,2′-bipyridyl ligands were synthesized and characterized. The electrogenerated chemiluminescence (ECL) of the rhenium(I) carbonyl complexes was first investigated in aqueous solution using the co-reactant tri-n-propylamine (TPrA). The ECL behavior of the complexes was also studied in the presence of several surfactants. The oxidation of both TPrA and the rhenium(I) complexes was facilitated in the presence of Triton X-100, and the ECL intensity was enhanced 300-fold at a Au electrode. [Copyright &y& Elsevier]

Electron-transfer(ET) from organic sulfides to excited state rhenium(I)-based heteroleptic tricarbonyl complexes [Re(bpy)(CO)(py)] ( I) and [Re(bpy)(CO)(ind))] ( II) in acetonitrile solution is facile and luminescence quenching constants, k, are in the range 10-10 Ms. The detection of the sulfide radical cation in this system using time-resolved absorption spectroscopy is a direct evidence for the ET nature of the reaction. The k values for the quenching of Re(I)-complexes with organic sulfides are analyzed with a scheme involving rate controlling electron transfer process. The measured rate constants for the electron transfer (ET) reaction are close to the values calculated from Marcus theory. [ABSTRACT FROM AUTHOR]

Cell death is essential for cancer, which can be induced through multiple mechanisms. Ferroptosis, a newly emerging form of non-apoptotic cell death, involves the generation of iron-dependent reactive oxygen species (ROS). In this study, we designed and synthesized two artesunate (ART) conjugated phosphorescent rhenium(I) complexes (Re(I)-ART conjugates), [Re(N^N)(CO) 3 (PyCH 2 OART)](PF 6) (Re-ART-1 and Re-ART-2) (Py = pyridine, N^N = 1,10-phenanthroline (phen, in Re-ART-1) and 4,7-diphenyl-1,10-phenanthroline (DIP, in Re-ART-2)) that can specifically locate in the mitochondria of human cervical carcinoma (HeLa). Mechanism studies show that Re-ART-1 and Re-ART-2 exhibit high cytotoxicity against cancer cells lines and can induce both apoptosis and ferroptosis in HeLa cells through mitochondrial damage, caspase cascade, glutathione (GSH) depletion, glutathione peroxidase 4 (GPX4) inactivation and lipid peroxidation accumulation. As a result, this work presents the rational design of Re(I)-ART conjugates as a promising strategy to induce both apoptosis and ferroptosis and improve therapeutic efficiency of cancer treatment. [Display omitted] • Two Re(I)-artesunate (ART) conjugates were designed and synthesized. • Re(I)-ART conjugates specifically localized in mitochondria of Hela cells. • Re(I)-ART conjugates induced bimodal death through apoptosis and ferroptosis. [ABSTRACT FROM AUTHOR]

In this work, two classes of Carbonic Anhydrase (CA) inhibitors, sulfonamide and coumarin derivatives linked to pyta moiety (2a-b) and their corresponding rhenium complexes (3a-b), were designed. These compounds were synthesized and fully characterized by classical analytical methods and X-ray diffraction. All the synthesized compounds were evaluated for their inhibitory activity against the hCA isoforms I, II, IX and XII. They exhibited high inhibitory activities in the range of nanomolar for both hCA IX and hCA XII isoforms. The sulfonamide compound 2a showed the strongest inhibition against the tumour-associated hCA IX isoform with a Ki of 11.7 nM. The tumour-associated isoforms hCA IX and hCA XII were selectively inhibited by all the coumarin derivatives, with inhibition constants ranging from 12.7 nM (2b) to 44.5 nM (3b), while the hCA I and II isoforms were slightly inhibited (in the micromolar range), as expected. In terms of selectivity, compared to previously published rhenium complex-based CA inhibitors, complex 3b showed one of the highest selectivities against hCA IX and hCA XII compared to the off-target isoforms hCA I and hCA II, making it a potential anti-cancer drug candidate. Molecular docking calculations were performed to investigate the inhibition profiles of the investigated compounds at the tumour-associated hCA IX active site and to rationalize our results. [ABSTRACT FROM AUTHOR]

In this paper, imidazole N -alkylation (allyl and n -butyl) and the following rhenium(I) complexation strategy have been used for 2-(2-thienyl)imidazo[4,5- f ][1,10]-phenanthroline (TIP) to generate two aggregation-induced emission (AIE) active rhenium(I) tricarbonyl complexes Re2 and Re3. The destroy of planarity and conjugation of TIP by introducing alkyl chains and the increase of steric hindrance via implanting octahedral Re(I) coordination sphere lead to the restrictions of intramolecular rotation and formation of intermolecular π-π stacking, which could be the main reasons for the AIE activation. X-ray single-crystal structures of Re1 and Re2 verify the increase of dihedral angle in the TIP skeleton from 10.8(5)o to 22.7(1)o as well as the different crystal packing fashions (AAAA vs ABAB) after introducing the spatial crowding allyl group. Further studies reveal that the above-mentioned simultaneous modifications are vital for the AIE generation because control experiments show that either single imidazole N -alkylation (L2 and L3) or single rhenium(I) tricarbonyl complexation (Re1) gives rise to the typical aggregation-caused fluorescence quenching. To the best of our knowledge, this is the first report on Re(I)-TIP complexes and corresponding dual functionality for the AIE activation. Image 1 • N -alkylation and Re(I) complexation are performed to prepare TIP derivatives. • Dual functionality for the planar TIP molecule to generate AIE is achieved. • AIE mechanism is described based on crystal structures and spectral observations. [ABSTRACT FROM AUTHOR]