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When reacted in dry, degassed toluene, [Ir(COD)Cl]2 (COD = cyclo­octa-1,5-diene) and 2 equivalents of 2-(di-tert-butyl­phosphinito)anthra­quinone (tBuPOAQH) were found to form a unique tri-iridium compound consisting of one monoanionic dinuclear tri-μ-chlorido complex bearing one bidentate tBuPOAQ ligand per iridium, which was charge-balanced by an outer sphere [Ir(toluene)(COD)]+ ion, the structure of which has not previously been reported. This product, which is a toluene solvate, namely, (η²:η²-cyclo­octa-1,5-diene)(η6-toluene)­iridium(I) tri-μ-chlorido-bis­({3-[(di-tert-butyl­phosphan­yl)­oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(III)) toluene monosolvate, [Ir(C7H8)(C8H12)][Ir2H2(C22H24O3P)2Cl3]·C7H8 or [Ir(toluene)(COD)][Ir(κ-P,C-tBuPOAQ)(H)]2(μ-Cl)3]·toluene, formed as small orange platelets at room temperature, crystallizing in the triclinic space group P1. The cation and anion are linked via weak C—H⋯O inter­actions. The stronger inter­molecular attractions are likely the offset parallel π–π inter­actions, which occur between the toluene ligands of pairs of inverted cations and between pairs of inverted anthra­quinone moieties, the latter of which are capped by toluene solvate mol­ecules, making for π-stacks of four mol­ecules each. The related ligand, 2-(di-tert-butyl­phosphinometh­yl)-anthra­quinone (tBuPCAQH), did not form crystals suitable for X-ray diffraction under analogous reaction conditions. However, when the reaction was conducted in chloro­form, yellow needles readily formed following addition of 1 atm of carbon monoxide. Diffraction studies revealed a neutral, dinuclear, di-μ-chlorido complex, di-μ-chlorido-bis­(carbon­yl{3-[(di-tert-butyl­phosphan­yl)­oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(I)), [Ir2H2(C23H26O2P)2Cl2(CO)2] or [Ir(κ-P,C-tBuPCAQ)(H)(CO)(μ-Cl)]2, Ir2C48H54Cl2O6P2, again crystallizing in space group P1. Offset parallel π–π inter­actions between anthra­quinone groups of adjacent mol­ecules link the mol­ecules in one dimension. [ABSTRACT FROM AUTHOR]

When reacted in dry, degassed toluene, [Ir(COD)Cl]2 (COD = cyclo­octa-1,5-diene) and 2 equivalents of 2-(di-tert-butyl­phosphinito)anthra­quinone (tBuPOAQH) were found to form a unique tri-iridium compound consisting of one monoanionic dinuclear tri-μ-chlorido complex bearing one bidentate tBuPOAQ ligand per iridium, which was charge-balanced by an outer sphere [Ir(toluene)(COD)]+ ion, the structure of which has not previously been reported. This product, which is a toluene solvate, namely, (η²:η²-cyclo­octa-1,5-diene)(η6-toluene)­iridium(I) tri-μ-chlorido-bis­({3-[(di-tert-butyl­phosphan­yl)­oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(III)) toluene monosolvate, [Ir(C7H8)(C8H12)][Ir2H2(C22H24O3P)2Cl3]·C7H8 or [Ir(toluene)(COD)][Ir(κ-P,C-tBuPOAQ)(H)]2(μ-Cl)3]·toluene, formed as small orange platelets at room temperature, crystallizing in the triclinic space group P[\overline{1}]. The cation and anion are linked via weak C--H⋯O inter­actions. The stronger inter­molecular attractions are likely the offset parallel π-π inter­actions, which occur between the toluene ligands of pairs of inverted cations and between pairs of inverted anthra­quinone moieties, the latter of which are capped by toluene solvate mol­ecules, making for π-stacks of four mol­ecules each. The related ligand, 2-(di-tert-butyl­phosphinometh­yl)-anthra­quinone (tBuPCAQH), did not form crystals suitable for X-ray diffraction under analogous reaction conditions. However, when the reaction was conducted in chloro­form, yellow needles readily formed following addition of 1 atm of carbon monoxide. Diffraction studies revealed a neutral, dinuclear, di-μ-chlorido complex, di-μ-chlorido-bis­(carbon­yl{3-[(di-tert-butyl­phosphan­yl)­oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(I)), [Ir2H2(C23H26O2P)2Cl2(CO)2] or [Ir(κ-P,C-tBuPCAQ)(H)(CO)(μ-Cl)]2, Ir2C48H54Cl2O6P2, again crystallizing in space group P[\overline{1}]. Offset parallel π-π inter­actions between anthra­quinone groups of adjacent mol­ecules link the mol­ecules in one dimension. [ABSTRACT FROM AUTHOR]

When reacted in dry, degassed toluene, [Ir(COD)Cl]2 (COD = cycloocta-1,5-diene) and 2 equivalents of 2-(di-tert-butylphosphinito)anthraquinone (tBuPOAQH) were found to form a unique tri-iridium compound consisting of one monoanionic dinuclear tri-μ-chlorido complex bearing one bidentate tBuPOAQ ligand per iridium, which was charge-balanced by an outer sphere [Ir(toluene)(COD)]+ ion, the structure of which has not previously been reported. This product, which is a toluene solvate, namely, (η2:η2-cycloocta-1,5-diene)(η6-toluene)iridium(I) tri-μ-chlorido-bis({3-[(di-tert-butylphosphanyl)oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(III)) toluene monosolvate, [Ir(C7H8)(C8H12)][Ir2H2(C22H24O3P)2Cl3]·C7H8 or [Ir(toluene)(COD)][Ir(κ-P,C-tBuPOAQ)(H)]2(μ-Cl)3]·toluene, formed as small orange platelets at room temperature, crystallizing in the triclinic space group P\overline{1}. The cation and anion are linked via weak C—H...O interactions. The stronger intermolecular attractions are likely the offset parallel π–π interactions, which occur between the toluene ligands of pairs of inverted cations and between pairs of inverted anthraquinone moieties, the latter of which are capped by toluene solvate molecules, making for π-stacks of four molecules each. The related ligand, 2-(di-tert-butylphosphinomethyl)-anthraquinone (tBuPCAQH), did not form crystals suitable for X-ray diffraction under analogous reaction conditions. However, when the reaction was conducted in chloroform, yellow needles readily formed following addition of 1 atm of carbon monoxide. Diffraction studies revealed a neutral, dinuclear, di-μ-chlorido complex, di-μ-chlorido-bis(carbonyl{3-[(di-tert-butylphosphanyl)oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(I)), [Ir2H2(C23H26O2P)2Cl2(CO)2] or [Ir(κ-P,C-tBuPCAQ)(H)(CO)(μ-Cl)]2, Ir2C48H54Cl2O6P2, again crystallizing in space group P\overline{1}. Offset parallel π–π interactions between anthraquinone groups of adjacent molecules link the molecules in one dimension.

Trinuclear metallacyclic oxidovanadium(V) complexes, [{VO(L3+2R)}3] (1–3) with asymmetric multidentate linking ligands (H3L3+2R: R = H, Me, Br), were synthesized. The molecular structure of 1 is characterized as a tripod structure, with each V(V) ion coordinated by ONO-atoms from a tridentate Schiff base site and ON-atoms from a bidentate benzoxazole site of two respective H3L3+2H ligands. The intramolecular V⋯V distances range from 8.0683 to 8.1791 Å. Complex 4 is a mononuclear dioxidovanadium(V) complex, (Et3NH)[VO2(HL3+2H)]. Cyclic voltammograms of 1−3 in DMF revealed redox couples attributed to three single-electron transfer processes. [ABSTRACT FROM AUTHOR]

[Display omitted] It is still challenging to develop multi–step cascaded artificial light–harvesting systems (ALHSs) with tunable efficiency. Here, we designed novel cascaded ALHSs with AIE–active metallacycles as the light–harvesting antenna, Eosin Y (ESY) and sulforhodamine 101 (SR101) as conveyors, near–infrared emissive chlorin–e6 (Ce6) as the final acceptor. The close contact and fair spectral overlap between donor and acceptor molecules at each level ensured the efficient sequential three–step energy transfer. The excited energy was sequentially and efficiently funneled to Ce6 along the cascaded line MTPEPt1 → ESY → SR101 → Ce6. Additionally, a unique strategy for regulating the efficiency of ALHS was illustrated by adjusting hydrophilic and hydrophobic interactions. [ABSTRACT FROM AUTHOR]

The macrometallacyclic title compound, [Hg4Br4(C8H11N2S)4] or [((HgL2)(HgBr2))2] (1) where HL = 2-{[(pyridin-2-yl)methyl]amino}ethane-1-thiol, was prepared and structurally characterized. The Hg2+ complex crystallizes in the P21/c space group. The centrosymmetric Hg4S4 metallacycle is constructed from metal ions with alternating distorted tetrahedral Br2S2 and distorted seesaw N2S2 primary coordination environments with pendant pyridyl groups. The backfolded extended chair metallacycle conformation suggests interactions between each of the bis-chelated mercury atoms and Br atoms lying above and below the central Hg2S4 plane. Supramolecular interactions in 1 include a fourfold aryl embrace and potential hydrogen bonds with bromine as the acceptor. Hirshfeld surface analysis indicates that H...H (51.7%), Br...H/H...Br (23.0%) and C...H/H...C (9.5%) interactions are dominant.

The macrometallacyclic title compound, [Hg4Br4(C8H11N2S)4] or [((HgL2)(HgBr2))2] (1) where HL = 2-{[(pyridin-2-yl)methyl]amino}ethane-1-thiol, was prepared and structurally characterized. The Hg2+ complex crystallizes in the P21/c space group. The centrosymmetric Hg4S4 metallacycle is constructed from metal ions with alternating distorted tetrahedral Br2S2 and distorted seesaw N2S2 primary coordination environments with pendant pyridyl groups. The backfolded extended chair metallacycle conformation suggests interactions between each of the bis-chelated mercury atoms and Br atoms lying above and below the central Hg2S4 plane. Supramolecular interactions in 1 include a fourfold aryl embrace and potential hydrogen bonds with bromine as the acceptor. Hirshfeld surface analysis indicates that H• • •H (51.7%), Br• • •H/ H• • •Br (23.0%) and C• • •H/H• • •C (9.5%) interactions are dominant. [ABSTRACT FROM AUTHOR]

Ruthenium complexes of phosphinocarboxamide ligands, and their use to form metallacycles using halide abstraction/deprotonation reactions are reported. Thus, [Ru(p-cym){PPh2C(=O)NHR}Cl2; R = iPr (1), Ph (2), p-tol (3)] and [Ru(p-cym){PPh2C(=O)N(R)C(=O)N(H)R}Cl2; R = Ph (4), p-tol (5)] were synthesized from [(p-cym)RuCl2]2 (p-cym = para-cymene) and phosphinocarboxamides or phosphinodicarboxamides, respectively. Single-crystal X-ray diffraction measurements on 1–5 reveal coordination to ruthenium through the phosphorus donor, with an intramolecular hydrogen bond between the amine-bound proton and a metal-bound chloride. Six-membered metallacycles formed by halide abstraction/deprotonation of complexes 4 and 5 afforded [Ru(p-cym){κ2-P,N-PPh2C(=O)N(R)C(=O)NR}Cl] [R = Ph (6), p-tol (7)]. These species exist as a mixture of two rotational isomers in solution, as demonstrated by NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Trinuclear metallacyclic oxidovanadium(V) complexes, [{VO(L3+2R)}3] (1–3) with asymmetric multidentate linking ligands (H3L3+2R: R = H, Me, Br), were synthesized. The molecular structure of 1 is characterized as a tripod structure, with each V(V) ion coordinated by ONO-atoms from a tridentate Schiff base site and ON-atoms from a bidentate benzoxazole site of two respective H3L3+2H ligands. The intramolecular V⋯V distances range from 8.0683 to 8.1791 Å. Complex 4 is a mononuclear dioxidovanadium(V) complex, (Et3NH)[VO2(HL3+2H)]. Cyclic voltammograms of 1−3 in DMF revealed redox couples attributed to three single-electron transfer processes.

Assembling metallacycles with interesting topological arrangements is a critical task for chemists. We report here a novel dodecanuclear CuII compound, [{Cu3L(µ-N3)}4(Py)14]·2Py (Cu12) (where Py = pyridine and [H6L]Cl = tris(2-hydroxybenzylidine)triaminoguanidinium chloride, respectively), with the topology of a cycle accomplished by four two-connecting approximately flat C3-symmetric guanidine-based ligands. Each ligand affords three tridentate metal-binding cavities and the four node-to-node connections through single azido bridges are provided by pairs of metal centers. A theoretical investigation using CASSCF in addition to DFT calculations showed strong antiferromagnetic coupling within the Cu3-triangles, resulting in spin-frustrated systems. However, these calculations were not able to properly reproduce the very weak antiferromagnetic couplings between the triangle units, highlighting the challenge of describing the magnetic behavior of this compound. [ABSTRACT FROM AUTHOR]

Ruthenium complexes of phosphinocarboxamide ligands, and their use to form metallacycles using halide abstraction/deprotonation reactions are reported. Thus, [Ru(p-cym){PPh2C(=O)NHR}Cl2; R = iPr (1), Ph (2), p-tol (3)] and [Ru(p-cym){PPh2C(=O)N(R)C(=O)N(H)R}Cl2; R = Ph (4), p-tol (5)] were synthesized from [(p-cym)RuCl2]2 (p-cym = para-cymene) and phosphinocarboxamides or phosphinodicarboxamides, respectively. Single-crystal X-ray diffraction measurements on 1–5 reveal coordination to ruthenium through the phosphorus donor, with an intramolecular hydrogen bond between the amine-bound proton and a metal-bound chloride. Six-membered metallacycles formed by halide abstraction/deprotonation of complexes 4 and 5 afforded [Ru(p-cym){κ2-P,N-PPh2C(=O)N(R)C(=O)NR}Cl] [R = Ph (6), p-tol (7)]. These species exist as a mixture of two rotational isomers in solution, as demonstrated by NMR spectroscopy.

Supramolecular polymers based on supramolecular coordination complexes (SCCs) have received extensive attention because of their good stimulus responsiveness, processability and other properties. Herein, we report metallacycle-crosslinked supramolecular polymers via amino–yne click reaction, which were employed as well-performing elastomer materials. The supramolecular polymers cross-linked by the metallacycle not only maintained the aggregation induced emission (AIE) properties of the metallacycle, which were used to detect nitroaromatic explosives, but also had enhanced mechanical strength and toughness and exhibited elastomeric properties. This study provides a feasible strategy for the preparation of metallacycle-based supramolecular polymers with better mechanical properties.

When reacted in dry, degassed toluene, [Ir(COD)Cl] 2 (COD = cyclo-octa-1,5-diene) and 2 equivalents of 2-(di- tert -butyl-phosphinito)anthra-quinone ( tBu POAQH) were found to form a unique tri-iridium compound consisting of one monoanionic dinuclear tri-μ-chlorido complex bearing one bidentate tBu POAQ ligand per iridium, which was charge-balanced by an outer sphere [Ir(toluene)(COD)] + ion, the structure of which has not previously been reported. This product, which is a toluene solvate, namely, (η 2 :η 2 -cyclo-octa-1,5-diene)(η 6 -toluene)-iridium(I) tri-μ-chlorido-bis-({3-[(di- tert -butyl-phosphan-yl)-oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(III)) toluene monosolvate, [Ir(C 7 H 8 )(C 8 H 12 )][Ir 2 H 2 (C 22 H 24 O 3 P) 2 Cl 3 ]·C 7 H 8 or [Ir(toluene)(COD)][Ir(κ- P , C - tBu POAQ)(H)] 2 (μ-Cl) 3 ]·toluene, formed as small orange platelets at room temperature, crystallizing in the triclinic space group P . The cation and anion are linked via weak C-H⋯O inter-actions. The stronger inter-molecular attractions are likely the offset parallel π-π inter-actions, which occur between the toluene ligands of pairs of inverted cations and between pairs of inverted anthra-quinone moieties, the latter of which are capped by toluene solvate mol-ecules, making for π-stacks of four mol-ecules each. The related ligand, 2-(di- tert -butyl-phosphinometh-yl)-anthra-quinone ( tBu PCAQH), did not form crystals suitable for X-ray diffraction under analogous reaction conditions. However, when the reaction was conducted in chloro-form, yellow needles readily formed following addition of 1 atm of carbon monoxide. Diffraction studies revealed a neutral, dinuclear, di-μ-chlorido complex, di-μ-chlorido-bis-(carbon-yl{3-[(di- tert -butyl-phosphan-yl)-oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(I)), [Ir 2 H 2 (C 23 H 26 O 2 P) 2 Cl 2 (CO) 2 ] or [Ir(κ- P , C - tBu PCAQ)(H)(CO)(μ-Cl)] 2 , Ir 2 C 48 H 54 Cl 2 O 6 P 2 , again crystallizing in space group P . Offset parallel π-π inter-actions between anthra-quinone groups of adjacent mol-ecules link the mol-ecules in one dimension., (© Thackeray et al. 2024.)

Ruthenium (Ru) complexes are developed as latent emissive photosensitizers for cancer and pathogen photodiagnosis and therapy. Nevertheless, most existing Ru complexes are limited as photosensitizers in terms of short excitation and emission wavelengths. Herein, we present an emissive Ru(II) metallacycle (herein referred to as 1) that is excited by 808-nm laser and emits at a wavelength of ~1,000 nm via coordinationdriven self-assembly. Metallacycle 1 exhibits good optical penetration (~7 mm) and satisfactory reactive oxygen species production properties. Furthermore, 1 shows broadspectrum antibacterial activity (including against drug-resistant Escherichia coli) as well as low cytotoxicity to normal mammalian cells. In vivo studies reveal that 1 is employed in precise, second near-infrared biomedical window fluorescent imaging-guided, photo-triggered treatments in Staphylococcus aureus-infected mice models, with negligible side effects. This work thus broads the applications of supramolecular photosensitizers through the strategy of lengthening their wavelengths. [ABSTRACT FROM AUTHOR]

Although boron dipyrromethene (BODIPY)-based metallacycles are expected to be promising candidates for imaging probes and therapeutic agents, their biomedical applications are restricted by their short absorption/emission wavelengths. In this work, we report a rhombic metallacycle M with broad absorption in the near-infrared (NIR) range and emissions at wavelengths >800 nm, which exhibits an efficient photothermal conversion capacity. Metallacycle M was encapsulated via Pluronic F127 to fit the biotic environment, resulting in the generation of F127/M nanoparticles (NPs) with high hydrophilicity and biocompatibility. In vitro studies demonstrated that the F127/M NPs underwent efficient cellular uptake and exhibited satisfactory photothermal therapeutic activity. Furthermore, in vivo experiments revealed that tumor growth was effectively inhibited, and the degree of undesirable biological damage was minimal in treatment with F127/M NPs and laser irradiation. Finally, the F127/M NPs could be visualized through NIR fluorescence imaging in living mice, thereby allowing their distribution to be monitored in order to enhance treatment accuracy during photothermal therapy. We envision that such BODIPY-based metallacycles will provide emerging opportunities for the development of novel therapeutic agents for biomedical applications. [ABSTRACT FROM AUTHOR]

Although platinum-based anticancer drugs have prevailed in traditional chemotherapy, the severe side effects and drug resistance hampered their clinical applications. Combinational therapies have exhibited promises in antitumor treatments. However, the integration of different anticancer modalities is often challenging because of the conflicts between maximal synergy of therapeutic effects and reduction of side effects. Here, we report a multifunctional platform composed of metallacycle-based star polymer and gold nanorods for synergistic photochemotherapy. We applied the Pt-based metallacycle-cored star polymers as both a photodynamic photosensitizer and a Pt-based anticancer drug. The gold nanorods play the dual role of photothermal converter and energy acceptor of fluorescence resonance energy transfer effect from the star polymers. The photothermal effect enhanced tumor permeability of reactive oxygen species and Pt-based drug molecules and the photodynamic effect destructed heat shock proteins to prevent the mechanism of cellular self-protection response to heat. This mutually beneficial strategy results in high therapeutic efficacy and negligible side effects verified by both in vitro and in vivo studies. This study offers a new avenue in designing a multifunctional platform for the synergy of different antitumor modalities.

Assembling metallacycles with interesting topological arrangements is a critical task for chemists. We report here a novel dodecanuclear CuII compound, [{Cu3L(µ-N3)}4(Py)14]·2Py (Cu12) (where Py = pyridine and [H6L]Cl = tris(2-hydroxybenzylidine)triaminoguanidinium chloride, respectively), with the topology of a cycle accomplished by four two-connecting approximately flat C3-symmetric guanidine-based ligands. Each ligand affords three tridentate metal-binding cavities and the four node-to-node connections through single azido bridges are provided by pairs of metal centers. A theoretical investigation using CASSCF in addition to DFT calculations showed strong antiferromagnetic coupling within the Cu3-triangles, resulting in spin-frustrated systems. However, these calculations were not able to properly reproduce the very weak antiferromagnetic couplings between the triangle units, highlighting the challenge of describing the magnetic behavior of this compound.

Transition metal-mediated templating and self-assembly have shown great potential to construct mechanically interlocked molecules. Herein, we describe the formation of the bimetallic [3]catenane and [4]catenane based on neutral organometallic scaffolds via the orthogonality of platinum-to-oxygen coordination-driven self-assembly and copper(I) template–directed strategy of a [2]pseudorotaxane. The structures of these bimetallic [3]catenane and [4]catenane were characterized by multinuclear NMR {1H and 31P} spectroscopy, electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), and PM6 semiempirical molecular orbital theoretical calculations. In addition, single-crystal X-ray analyses of the [3]catenane revealed two asymmetric [2]pseudorotaxane units inside the metallacycle. It was discovered that tubular structures were formed through the stacking of individual [3]catenane molecules driven by the strong π–π interactions.

• Exocyclic alkenyl ylide phenolate and benzoate Re (V) complexes. • Polycyclic rhenacycloprop-2-ene Re (III) complexes. • P-C bond cleavage during reductions of alkenyl ylide phenolate Re (V) complexes. Additions of nucleophiles like phosphines to coordinated alkynes are important processes in organometallic synthesis. In this work, exocyclic alkenyl ylide phenolate (1–2) and benzoate (5) Re(V) complexes are obtained from the reactions of internal 2-alkynylphenols, and 2-ethynylbenzoic acid with ReOCl 2 (OEt)(PPh 3) 2 , respectively. The Re(V) complexes 1–2 can be reduced to η 2-alkyne Re(III) complexes 3–4 with P-C bond cleavage. Exocyclic alkenyl ylide phenolate Re (V) complexes and polycyclic rhenacycloprop-2-ene Re (III) complexes have been produced from the reactions of internal 2-alkynylphenols with ReOCl 2 (OEt)(PPh 3) 2 under different conditions. The alkenyl ylide Re (V) complexes can be reduced to η 2-alkyne Re (III) complexes with P-C bond cleavage. [Display omitted] [ABSTRACT FROM AUTHOR]

Although boron dipyrromethene (BODIPY)-based metallacycles are expected to be promising candidates for imaging probes and therapeutic agents, their biomedical applications are restricted by their short absorption/emission wavelengths. In this work, we report a rhombic metallacycle M with broad absorption in the near-infrared (NIR) range and emissions at wavelengths >800 nm, which exhibits an efficient photothermal conversion capacity. Metallacycle M was encapsulated via Pluronic F127 to fit the biotic environment, resulting in the generation of F127/M nanoparticles (NPs) with high hydrophilicity and biocompatibility. In vitro studies demonstrated that the F127/M NPs underwent efficient cellular uptake and exhibited satisfactory photothermal therapeutic activity. Furthermore, in vivo experiments revealed that tumor growth was effectively inhibited, and the degree of undesirable biological damage was minimal in treatment with F127/M NPs and laser irradiation. Finally, the F127/M NPs could be visualized through NIR fluorescence imaging in living mice, thereby allowing their distribution to be monitored in order to enhance treatment accuracy during photothermal therapy. We envision that such BODIPY-based metallacycles will provide emerging opportunities for the development of novel therapeutic agents for biomedical applications.

Despite the widespread clinical application of chemotherapeutic anticancer drugs, their adverse side effects and inefficient performances remain ongoing issues. A drug delivery system (DDS) designed for a specific cancer may therefore overcome the drawbacks of single chemotherapeutic drugs and provide precise and synergistical cancer treatment by introducing exclusive stimulus responsiveness and combined chemotherapy properties. Herein, we report the design and synthesis of a supramolecular drug delivery assembly 1 constructed by orthogonal self-assembly technique in aqueous media specifically for application in liver cancer therapy. Complex 1 incorporates the β-cyclodextrin host moleculefunctionalized organoplatinum(II) metallacycle 2 with two specific stimulus-responsive motifs to the signaling molecule nitric oxide (NO), in addition to the three-armed polyethylene glycol (PEG) functionalized ferrocene 3 with redox responsiveness. With this molecular design, the particularly low critical aggregation concentration (CAC) of assembly 1 allowed encapsulation of the commercial anticancer drug doxorubicin (DOX). Controlled drug release was also achieved by morphological transfer via a sensitive response to the endogenous redox and NO stimuli, which are specifically related to the microenvironment of liver tumor cells. Upon combination of these properties with the anticancer ability from the platinum acceptor, in vitro studies demonstrated that DOX-loaded 1 is able to codeliver anticancer drugs and exhibit therapeutic effectiveness to liver tumor sites via a synergistic effect, thereby revealing a potential DDS platform for precise liver cancer therapeutics. [ABSTRACT FROM AUTHOR]

In this review, we describe the synthesis and use in hydrogen transfer reactions of ruthenacycles and iridacycles. The review limits itself to metallacycles where a ligand is bound in bidentate fashion to either ruthenium or iridium via a carbon–metal sigma bond, as well as a dative bond from a heteroatom or an N-heterocyclic carbene. Pincer complexes fall outside the scope. Described are applications in (asymmetric) transfer hydrogenation of aldehydes, ketones, and imines, as well as reductive aminations. Oxidation reactions, i.e., classical Oppenauer oxidation, which is the reverse of transfer hydrogenation, as well as dehydrogenations and oxidations with oxygen, are described. Racemizations of alcohols and secondary amines are also catalyzed by ruthenacycles and iridacycles.

In this work, we investigate the self-assembly between Ag(I) and Au(I) centers and pyridyl donors to form hexagonal metallacycles and related linear complexes. The precipitation of hexagonal metallacycles upon assembly in chloroform/methanol mixtures results in high solid-state photo-stability. Whereas, the Ag(I) species have fast kinetics and high formation constants in acetone, this solvent interferes in the formation of the analogous Au(I) complexes. The photophysical properties of this suite of metallacycles was investigated including steady-state absorption, emission, and time-resolved lifetime measurements. All ligands and hexagons exhibited ligand-centered singlet emissions with ground-state absorption and emission perturbed upon coordination. The ligand-based fluorescent photoluminescence was affected by the heavy-atom effect when halide or metals are present, attenuating quantum yields as evidenced by increases in the experimentally measured non-radiative rate constants. The formation of group 11 metallacycles is motivated by their potential applications in mixed-matrix materials wherein metal ions can interact with substrate to facilitate separations chemistry with reduced energy requirements, in particular the isolation of ethylene and light olefins. Existing processes involve cryogenic distillation, an energy intensive and inefficient method.

The design and development of metallosupramolecular systems has resulted in construction of a myriad of fascinating structures with highly diverse properties and potential applications. Assessment of the biomedical applications of metallosupramolecular assemblies is an emerging field of research that stems from the recently demonstrated promising results on such systems. After the pioneering works of Therrien and coworkers on organometallic Ru-cages with promising anticancer properties, this topic has evolved to the more recent studies on bioactivity of supramolecular coordination complexes built from different metal ions and various multidentate ligands. Sufficient amount of data on the anticancer activity of metallosupramolecules has already been reported and allows outlining some general tendencies in the structural aspects of the biological activity. The main structural properties of the complexes that can be readily modified to enhance their activity are the size, the shape and charge of the formed complexes. Moreover, the intrinsic properties of the building components could predetermine some of the main characteristics of the overall supramolecular complex, such as its optical properties, chemical reactivity, solubility, etc., and could, thereby, define the areas of its biomedical applications. The unique structural property of most of the metallosupramolecular assemblies, however, is the presence of a discrete cavity that renders a whole range of additional applications resulting from specific host-guest interactions. The encapsulations of small bioactive or fluorescent molecules have been employed for delivery or recognition purposes in many examples. On the other hand, metallosupramolecules have been imbedded into target-specific polymeric nanoparticles that resulted in a successful combination of their therapeutic and diagnostic properties, making them promising for theranostic application in cancer treatment. The aim of this review paper is to mark out some key tendencies in the reported metallosupramolecular structures in relation with their biological activity and potential areas of biomedical application. In this way, a useful set of guidelines can be delineated to help synthetic chemists broaden the application areas of their supramolecular systems by few structural changes.

Discrete Pt(II) metallacycles have potential applications in bio-medicine. Herein, we engineered a dual-modal imaging and chemo-photothermal therapeutic nano-agent 1 that incorporates discrete Pt(II) metallacycle 2 and fluorescent dye 3 (emission wavelength in the second near-infrared channel [NIR-II]) into multifunctional melanin dots with photoacoustic signal and photothermal features. Nano-agent 1 has a good solubility, biocompatibility, and stability in vivo. Both photoacoustic imaging and NIR-II imaging in vivo confirmed that 1 can effectively accumulate at tumor sites with good signal-to-background ratio and favorable distribution. Guided by precise dual-modal imaging, nano-agent 1 exhibits a superior antitumor performance and less severe side effects compared with a single treatment because of the high efficiency of the chemo-photothermal synergistic therapy. This study shows that nano-agent 1 provides a promising multifunctional theranostic platform for potential applications in biomedicine. [ABSTRACT FROM AUTHOR]

The precise operation of molecular motion for constructing complicated mechanically interlocked molecules has received considerable attention and is still an energetic field of supramolecular chemistry. Herein, we reported the construction of two tris[2]pseudorotaxanes metallacycles with acid–base controllable molecular motion through self-sorting strategy and host–guest interaction. Firstly, two hexagonal Pt(II) metallacycles M1 and M2 decorated with different host–guest recognition sites have been constructed via coordination-driven self-assembly strategy. The binding of metallacycles M1 and M2 with dibenzo-24-crown-8 (DB24C8) to form tris[2]pseudorotaxanes complexes TPRM1 and TPRM2 have been investigated. Furthermore, by taking advantage of the strong binding affinity between the protonated metallacycle M2 and DB24C8, the addition of trifluoroacetic acid (TFA) as a stimulus successfully induces an acid-activated motion switching of DB24C8 between the discrete metallacycles M1 and M2. This research not only affords a highly efficient way to construct stimuli-responsive smart supramolecular systems but also offers prospects for precisely control multicomponent cooperative motion.

The macrometallacyclic title compound, [Hg 4 Br 4 (C 8 H 11 N 2 S) 4 ] or [((Hg L 2 )(HgBr 2 )) 2 ] ( 1 ) where HL = 2-{[(pyridin-2-yl)meth-yl]amino}-ethane-1-thiol, was prepared and structurally characterized. The Hg 2+ complex crystallizes in the P 2 1 / c space group. The centrosymmetric Hg 4 metallacycle is constructed from metal ions with alternating distorted tetra-hedral Br 4 metallacycle is constructed from metal ions with alternating distorted tetra-hedral Br 2 S 2 and distorted seesaw N 2 primary coordination environments with pendant pyridyl groups. The backfolded extended chair metallacycle conformation suggests inter-actions between each of the bis-chelated mercury atoms and Br atoms lying above and below the central Hg 2 primary coordination environments with pendant pyridyl groups. The backfolded extended chair metallacycle conformation suggests inter-actions between each of the bis-chelated mercury atoms and Br atoms lying above and below the central Hg 2 S 4 plane. Supra-molecular inter-actions in 1 include a fourfold aryl embrace and potential hydrogen bonds with bromine as the acceptor. Hirshfeld surface analysis indicates that H⋯H (51.7%), Br⋯H/H⋯Br (23.0%) and C⋯H/H⋯C (9.5%) inter-actions are dominant., (© Thomas et al. 2023.)

Dinuclear complexes with a metal-metal interaction have been extensively investigated as minimum entities of metal clusters. Hydrocarbon-bridged dinuclear complexes are one of the most important class of the dinuclear complexes for exploring any transformations of the unsaturated hydrocarbons at the dinuclear core. In this review, we summarize the dinuclear complexes with metal-metal interaction supported by unsaturated hydrocarbons such as alkynes, dienes, and aromatic compounds resulting in 3–6 membered metallacycles, and briefly discuss the structural characteristics based on the different metallacycle structures and coordination mode of the unsaturated hydrocarbons in the dinuclear complexes. [ABSTRACT FROM AUTHOR]

Curcumin (Cur) is a naturally occurring anticancer drug isolated from the Curcuma longa plant. It is known to exhibit anticancer properties via inhibiting the STAT3 phosphorylation process. However, its poor water solubility and low bioavailability impede its clinical application. Herein, we used organoplatinum(II) ← pyridyl coordination-driven self-assembly and a cucurbit[8]uril (CB[8])-mediated heteroternary host-guest complex formation in concert to produce an effective delivery system that transports Cur into the cancer cells. Specifically, a hexagon 1, containing hydrophilic methyl viologen (MV) units and 3,4,5-Tris[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]benzoyl groups alternatively at the vertices, has been synthesized and characterized by several spectroscopic techniques. The MV units of 1 underwent noncovalent complexation with CB[8] to yield a host-guest complex 4. Cur can be encapsulated in 4, via a 1:1:1 heteroternary complex formation, resulting in a water-soluble host-guest complex 5. The host-guest complex 5 exhibited ca. 100-fold improved IC50 values relative to free Cur against human melanoma (C32), melanoma of rodents (B16F10), and hormone-responsive (MCF-7) and triple-negative (MDA-MB231) breast cancer cells. Moreover, strong synergisms of Cur with 1 and 4 with combinatorial indexes of <1 across all of the cell lines were observed. An induced apoptosis with fragmented DNA pattern and inhibited expression of phosphor-STAT3 supported the improved therapeutic potential of Cur in heteroternary complex 5. [ABSTRACT FROM AUTHOR]

The reaction of [Co III (4,4′dmsalen)(CH 2 Cl)(L)], where 4,4′dmsalen = 4,4′-dimethylsalen and L = solvent, with pyridine led to the isolation of [Co III (4,4′dmsalen)(CH 2 py)(Cl)], in a two-step process involving a metallacyclized intermediate, cis β [Co III (4,4′dmsalenCH 2 )(py)(L)] + , whereas a parallel direct conversion through the displacement of a Cl atom from the axial CH 2 Cl group of [Co III (4,4′dmsalen)(CH 2 Cl)(L)] may be ruled out. Natural bond orbital analysis of the structures show that the ylide carbon atom has lower orbital occupancies in the cyclized complex, thus making it more susceptible to a nucleophilic attack of pyridine. The calculated potential energy surfaces indicate that the most energy feasible reaction path would be for the complex [Co III (4,4′dmsalenCH 2 )(py) ax (H 2 O)] + , with an entering pyridine molecule and a leaving equatorial water molecule. Experimental kinetic studies of the formation of the ylide complex starting from [Co III (4,4′dmsalenCH 2 )(py) eq (H 2 O)] + strongly suggest that it is possible to obtain the ylide complex through an alternative, less energetically favourable path. [ABSTRACT FROM AUTHOR]

A simple, highly efficient synthesis of a series of novel chiral non-racemic rigid tetracyclic phosphorus ligands, applicable in important chemical asymmetric transformations, was performed. In a tandem cross-coupling/C-H bond activation reaction, a well-recognised and readily available ligand (R,R)-NORPHOS was used as the starting material. The palladium complexes of new ligands were obtained and characterised on the example of a crystalline dichloropalladium complex of [(1R,2R,9S,10S,11R,12R)-4-phenyltetracyclo[8.2.1.02,9.03,8]trideca-3,5,7-triene-11,12-diyl]bis(diphenylphosphane). A notably high activity and stereoselectivity of the palladium catalysts based on the new ligands were confirmed in a model asymmetric allylic substitution reaction. Herein, we discuss the geometry of the palladium complexes formed and its impact on the efficiency of the catalysts. A comparison of their geometric features with other bis(phosphane) ligand complexes found in the Cambridge Structural Database and built density functional theory (DFT) commutated models is also presented and rationalised.

The asymmetric unit of the title compound, [Co(C24H30N2P2)(CO)3][Co(CO)4]·0.25C7H8, consists of two crystallographically independent cations with similar conformations, two anions, and one-half of a toluene molecule disordered about an inversion centre. In the cations, a Co/P/N/P four-membered slightly bent metallacycle is the key structural element. The pendant NH group is not coordinated to the CoI atom, which displays a distorted trigonal–bipyramidal coordination geometry. Weak interionic hydrogen bonds are observed between the NH groups and a carbonyl group of the tetrahedral [Co(CO)4]− anions.

We have previously reported the formation of fluorescent 2,5-bis(arylethynyl)rhodacyclopentadienes from the reaction of [Rh( κ 2 - O , O -acac)(PMe 3 ) 2 ] (acac = acetylacetonato) with α , ω -bis(arylbutadiynyl)alkanes. However, a second isomer series, namely phosphorescent rhodium biphenyl complexes, was also obtained from the same reaction mixture, which made purification of the 2,5-bis(arylethynyl)rhodacyclopentadienes challenging and led to low isolated yields. Herein, we describe a synthetic protocol to access the desired fluorescent rhodium complexes by reaction of [Rh( κ 2 - O , O -acac)(P( p -tolyl 3 ) 2 )] with α , ω -bis(arylbutadiynyl)alkanes, which gives exclusively 2,5-bis(arylethynyl)rhodacyclopentadienes, and subsequent phosphine ligand exchange. The rhodacyclopentadienes bearing P( p -tolyl 3 ) ligands have been investigated and compared to their PMe 3 analogs with regard to their photophysical properties, showing that the aromatic phosphine ligands enhance non-radiative decay from the singlet excited state S 1 , while no phosphorescence from T 1 is observed despite the presence of the heavy rhodium atom. One of the P( p -tolyl 3 ) ligands can also be exchanged for an N -heterocyclic carbene (NHC), leading to unsymmetrically coordinated rhodacyclopentadienes. [ABSTRACT FROM AUTHOR]

The oligomerization of the light olefins ethene, propene, and butenes into fuels and chemicals has been investigated and commercially practiced for many years. While the area appears on the surface to be mature, many advances have been made in recent years. In this feature article, I discuss the mechanisms of reaction and showcase catalysts and processes useful for oligomerization from both the open and patent literature. Commercially practiced processes are spotlighted. Among the catalysts utilized in the art are acidic catalysts such as solid phosphoric acid and zeolites, as well as metal based catalysts including aluminum alkyls, and nickel and zirconium based complexes and solids. A short section on catalysts and processes which utilize a metallacycle mechanism in order to achieve high selectivity to 1-hexene or 1-octene is followed by a discussion of multi-functional materials possessing both acid and metal active sites. Finally, processes where oligomerization is a key step in a multi-step or multi-reaction process are discussed. [ABSTRACT FROM AUTHOR]