Substituents' Effect on the Photophysics of Trinuclear Copper(I) and Silver(I) Pyrazolate-Phosphine Cages.

A series of structurally similar trinuclear macrocyclic copper(I) and silver(I) pyrazolate complexes bearing various short-bite diphosphine RPCH(R')PR ligands are reported. Upon diphosphine coordination, the planar geometry of the initial complexes undergoes bending along the line between two metal atoms coordinated to the phosphorus moieties. The complexes based on dcpm ligands (R = cyclohexyl, R' = H, Ph) do not exhibit dynamic behavior in solution at room temperature on the P NMR time scale as it was previously observed for similar trinuclear copper complexes bearing the dppm (R = Ph, R' = H) scaffold.

Biocompatible Re-Containing Block Copolymers for Intracellular pH Mapping in the PLIM Mode.

Monitoring of intracellular pH is of great importance since deviation of this parameter from the "normal" magnitudes can be considered as an indicator of various pathologies. Thus, the development of new efficient and biocompatible sensors suitable for application in biological systems and capable of quantitative pH estimation remains an urgent chemical task. Herein, we report the synthesis of a series of phosphorescent rhenium [Re(NN)(CO)(PR)] complexes based on the NN diimine ligands containing pH-responsive carboxylic groups and styrene-containing phosphine ligands.

Design and Preparation of Lifetime-Based Dual Fluorescent/Phosphorescent Sensor of pH and Oxygen and its Exploration in Model Physiological Solutions and Cells.

In the present report, a novel dual pH-O sensor based on covalent conjugate of rhodamine 6G and cyclometalated iridium complex with poly(vinylpyrrolidone-block-vinyltetrazole) copolymer is reported. In model physiological solutions the sensor chromophores display independent phosphorescent and fluorescent lifetime responses onto variations in oxygen concentration and pH, respectively. Colocalization studies on Chinese hamster ovary cells demonstrate the preferential localization in endosomes and lysosomes.

DPPM-Bridged Binuclear Pt(II) Pincer Complexes: Chemistry, Structure, and Photophysics in Solution Revisited.

A series of luminescent binuclear ([dppm{Pt(NNC)}]) and mononuclear ([PPhPt(NNC)]) complexes containing pincer ligands were synthesized and characterized. Photophysical characteristics of both types of complexes were studied in dichloromethane solution. In the solid phase, the binuclear compounds adopt a syn configuration where the {Pt(NNC)} fragments are held together due to intramolecular Pt-Pt bonding and π-stacking of the pincer ligand aromatic systems.

Unusual Effects of the Metal Center Coordination Mode on the Photophysical Behavior of the Rhenium(I) and Rhenium(I)-Iridium(III) Complexes.

Binuclear transition-metal complexes based on conjugated systems containing coordinating functions are potentially suitable for a wide range of applications, including light-emitting materials, sensors, light-harvesting systems, photocatalysts, etc., due to energy-transfer processes between chromophore centers. Herein we report on the synthesis, characterization, photophysical, and theoretical studies of relatively rare rhenium(I) and rhenium(I)-iridium(III) dyads prepared by using the nonsymmetrical polytopic ligands ( and ) with the strongly conjugated phenanthroline and imidazole-quinoline/pyridine coordinating fragments.

Rhenium(I) Block Copolymers Based on Polyvinylpyrrolidone: A Successful Strategy to Water-Solubility and Biocompatibility.

A series of diphosphine Re(I) complexes - have been designed via decoration of the archetypal core {Re(CO)(N^N)} through the installations of the phosphines and bearing the terminal double bond, where N^N = 2,2'-bipyridine (), 4,4'-di-tert-butyl-2,2'-bipyridine () or 2,9-dimethyl-1,10-phenanthroline () and = diphenylvinylphosphine, and = 4-(diphenylphosphino)styrene. These complexes were copolymerized with the corresponding N-vinylpyrrolidone-based Macro-RAFT agents of different polymer chain lengths to give water-soluble copolymers of low-molecular ) and high-molecular block-copolymers containing rhenium complexes. Compounds -, as well as the copolymers and , demonstrate phosphorescence from a MLCT excited state typical for this type of chromophores.

Polymeric Nanoparticles with Embedded Eu(III) Complexes as Molecular Probes for Temperature Sensing.

Three novel luminescent Eu(III) complexes, -, have been synthesized and characterized with CHN analysis, mass-spectrometry and H NMR spectroscopy. The complexes display strong emission in dichloromethane solution upon excitation at 405 and 800 nm with a quantum yield from 18.3 to 31.

Nonsymmetric [Pt(C^N*N'^C')] Complexes: Aggregation-Induced Emission in the Solid State and in Nanoparticles Tuned by Ligand Structure.

Invited for the cover of this issue are the groups of Sergey P. Tunik and his colleagues from St Petersburg University. The image depicts the strong bathochromic shift of the emission wavelength of phosphorescent platinum(II) complexes upon their aggregation in the presence of water.

Nonsymmetric [Pt(C^N*N'^C')] Complexes: Aggregation-Induced Emission in the Solid State and in Nanoparticles Tuned by Ligand Structure.

Five square-planar [Pt(C^N*N'^C')] complexes (Pt1-Pt5) with novel nonsymmetric tetradentate ligands (L1-L5) were synthesized and characterized. Varying the structure of the metalating aromatic systems result in substantial changes in photophysical properties and intermolecular interaction mode of the complexes in solution and in solid state. The complexes are strongly emissive in tetrahydrofuran solution, with the band maxima ranging from 560 to 690 nm.

Phosphorescent NIR emitters for biomedicine: applications, advances and challenges.

Application of NIR (near-infrared) emitting transition metal complexes in biomedicine is a rapidly developing area of research. Emission of this class of compounds in the "optical transparency windows" of biological tissues and the intrinsic sensitivity of their phosphorescence to oxygen resulted in the preparation of several commercial oxygen sensors capable of deep (up to whole-body) and quantitative mapping of oxygen gradients suitable for experimental studies. In addition to this achievement, the last decade has also witnessed the increased growth of successful alternative applications of NIR phosphors that include (i) site-specific and visualization of sophisticated biological models ranging from 3D cell cultures to intact animals; (ii) sensing of various biologically relevant analytes, such as pH, reactive oxygen and nitrogen species, RedOx agents, ; (iii) and several therapeutic applications such as photodynamic (PDT), photothermal (PTT), and photoactivated cancer (PACT) therapies as well as their combinations with other therapeutic and imaging modalities to yield new variants of combined therapies and theranostics.

Functionalizing Collagen with Vessel-Penetrating Two-Photon Phosphorescence Probes: A New In Vivo Strategy to Map Oxygen Concentration in Tumor Microenvironment and Tissue Ischemia.

The encapsulation and/or surface modification can stabilize and protect the phosphorescence bio-probes but impede their intravenous delivery across biological barriers. Here, a new class of biocompatible rhenium (Re ) diimine carbonyl complexes is developed, which can efficaciously permeate normal vessel walls and then functionalize the extravascular collagen matrixes as in situ oxygen sensor. Without protective agents, Re -diimine complex already exhibits excellent emission yield (34%, λ   = 583 nm) and large two-photon absorption cross-sections (σ   = 300 GM @ 800 nm) in water (pH 7.

Targeted Synthesis of NIR Luminescent Rhenium Diimine cis,trans-[Re( )(CO) (L) ] Complexes Containing N-Donor Axial Ligands: Photophysical, Electrochemical, and Theoretical Studies.

The combined action of ultraviolet irradiation and microwave heating onto acetonitrile solution of [Re( )(CO) (NCMe)]OTf ( =phenantroline and neocuproine) afforded cis,trans-Re( )(CO) (NCMe) ] acetonitrile derivatives. Substitution of relatively labile NCMe with a series of aromatic N-donor ligands (pyridine, pyrazine, 4,4'-bipyridine, N-methyl-4,4'-bipyridine) gave a novel family of the diimine cis,trans-[Re( )(CO) (L) ] complexes. Photophysical studies of the obtained compounds in solution revealed unusually high absorption across the visible region and NIR phosphorescence with emission band maxima ranging from 711 to 805 nm.

Design and synthesis of lipid-mimetic cationic iridium complexes and their liposomal formulation for and application in luminescent bioimaging.

Two iridium [Ir(N^C)(N^N)] complexes with the diimine N^N ligand containing a long polymethylene hydrophobic chain were synthesized and characterized by using NMR and ESI mass-spectrometry: N^N - 2-(1-hexadecyl-1-imidazol-2-yl)pyridine, N^C - methyl-2-phenylquinoline-4-carboxylate (Ir1) and 2-phenylquinoline-4-carboxylic acid (Ir2). These complexes were used to prepare the luminescent PEGylated DPPC liposomes (DPPC/DSPE-PEG2000/Ir-complex = 95/4.5/1 mol%) using a thin film hydration method.

Five- and Six-Coordinated Silver(I) Complexes Formed by a Metallomacrocyclic Ligand with a "AuN" Donor Group: Observation of Pendulum and Linear Motions and Dual Phosphorescence.

The six-coordinated silver(I) complex [AuAg(μ-(PPh)py)(OTf)](OTf), (py = pyridine, OTf = CFSO), and the five-coordinated silver(I) complex [AuAg(acetone)(μ-(PPh)py)](PF), , were prepared by the reaction of the precursor complexes (OTf) and (PF), in which = [Au(μ-(PPh)py)], with 1 equiv of Ag(OTf) in dichloromethane and excess of Ag(PF) in a mixture of dichloromethane/acetone, respectively. Also, the five-coordinated silver(I) complex [AuAg(μ-(PPh)py)(py)(OTf)](OTf), , was obtained by the reaction of with pyridine. The clusters - were characterized using multinuclear NMR spectroscopy and elemental microanalysis.

Neodymium β-diketonate showing slow magnetic relaxation and acting as a ratiometric thermometer based on near-infrared emission.

Self-assembly of β-diketonate (Htta = thenoyl(trifluoro)acetone) and 4,4'-azopyridine (Azo-py) with neodymium(iii) ions in the presence of methanol resulted in the formation of mononuclear complex [Nd(TTA)(MeOH)]·0.5Azo-py (A) in which two asymmetric units are linked by Azo-py through hydrogen bonding methanol. A reveals near-infrared emission (NIR) centred at about 895 and 1056 nm, in the 10-370 K temperature range, originating from the two emissive transitions on Nd(iii) from F to I and I levels, respectively.

Luminescent Complexes of the Trinuclear Silver(I) and Copper(I) Pyrazolates Supported with Bis(diphenylphosphino)methane.

The first example of trinuclear copper(I) and silver(I) pyrazolates adducts with a tertiary diphosphine (PhPCHPPh) retaining trimeric [MPz] core is reported. Despite rather strong M-P bonding, the complexes are able to undergo the dissociation of one M-P bond leading to the "merry-go-round" movement of P atoms over the M triangle. The copper complex displays emission from MLCT and MLCT states.

Efficient one-pot green synthesis of tetrakis(acetonitrile)copper(i) complex in aqueous media.

New simple, fast, effective and environmentally friendly one-pot method for the synthesis of extensively used tetrakis(acetonitrile)copper(i) complexes with BF , PF and ClO counterions is invented and optimized. The approach suggested allows using water as solvent and minimizes amounts of toxic organic reagents in the synthetic protocol.

Isoxazole Strategy for the Synthesis of 2,2'-Bipyridine Ligands: Symmetrical and Unsymmetrical 6,6'-Binicotinates, 2,2'-Bipyridine-5-carboxylates, and Their Metal Complexes.

An effective strategy was developed for the synthesis of new 2,2'-bipyridine ligands, symmetrical and unsymmetrical 6,6'-binicotinates, and 2,2'-bipyridine-5-carboxylates, from 4-propargylisoxazoles. The synthesis of symmetrical 2,2'-disubstituted 6,6'-binicotinates was achieved using the Eglinton reaction of 5-methoxy-4-(prop-2-yn-1-yl)isoxazoles with Cu(OAc), followed by Fe(NTf)/Au(NTf) tBuXPhos-catalyzed isomerization of the so-formed mixture of isoxazole/azirine-substituted biacetylenic intermediates. Unsymmetrical 2,2'-disubstituted 6,6'-binicotinates were prepared via a copper-free Sonogashira coupling of 5-methoxy-4-(prop-2-yn-1-yl)isoxazoles with 6-bromonicotinates to give methyl 6-(3-(5-methoxyisoxazol-4-yl)prop-1-ynyl)pyridine-3-carboxylates, followed by a transformation of the propargylisoxazole moiety of the adduct into the pyridine fragment under Fe(II)/Au(I) relay catalysis conditions.

Heterometallic Cluster-Capped Tetrahedral Assemblies with Postsynthetic Modification of the Metal Cores.

Combining the star-shaped alkynyl ligands with low-nuclearity gold-copper triphosphane clusters produces 3D metallocage aggregates, which demonstrate room temperature phosphorescence in solution (max Φ =0.6). Their luminescence mainly originates from cluster-localized metal-to-ligand charge transfer excited state.

Metalated Ir(III) Complexes Based on the Luminescent Diimine Ligands: Synthesis and Photophysical Study.

A series of novel diimine (NN) ligands containing developed aromatic [2,1- a]pyrrolo[3,2- c]isoquinoline system have been prepared and used in the synthesis of Ir(III) luminescent complexes. In organic solvents, the ligands display fluorescence which depends strongly on the nature of solvents to give moderate to strong orange emission in aprotic solvents and shows a considerable blue shift and substantial increase in emission intensity in methanol. Insertion of electron-withdrawing and -donating substituents into peripheral phenyl fragment has nearly no effect onto emission parameters.

Self-assemble nanoparticles based on polypeptides containing C-terminal luminescent Pt-cysteine complex.

The growing attention to the luminescent nanocarriers is strongly stimulated by their potential application as drug delivery systems and by the necessity to monitor their distribution in cells and tissues. In this communication we report on the synthesis of amphiphilic polypeptides bearing C-terminal phosphorescent label together with preparation of nanoparticles using the polypeptides obtained. The approach suggested is based on a unique and highly technological process where the new phosphorescent Pt-cysteine complex serves as initiator of the ring-opening polymerization of α-amino acid N-carboxyanhydrides to obtain the polypeptides bearing intact the platinum chromophore covalently bound to the polymer chain.

Synthesis and Intramolecular Azo Coupling of 4-Diazopyrrole-2-carboxylates: Selective Approach to Benzo and Hetero [c]-Fused 6H-Pyrrolo[3,4-c]pyridazine-5-carboxylates.

A high yield synthesis of fluorescent benzo, thieno, and furo [c]-fused methyl 7-aryl-6H-pyrrolo[3,4-c]pyridazine-5-carboxylates, including unprecedented heterocyclic skeletons, was performed by the transformation of methyl 4-aminopyrrole-2-carboxylate into the corresponding diazo compound, followed by intramolecular azo coupling under acid conditions onto a nucleophilic aryl or hetaryl group in the 3-position. Azo coupling is completely regioselective and, according to DFT calculations, a kinetically controlled reaction. N-Methylation of 1,3-disubstituted 2H-pyrrolo[3,4-c]cinnolines occurs selectively at N5 under kinetic control, leading exclusively to 5-methyl-5H-pyrrolo[3,4-c]cinnoline derivatives.

Coinage metal complexes supported by the tri- and tetraphosphine ligands.

A series of tri- and tetranuclear phosphine complexes of d(10) metal ions supported by the polydentate ligands, bis(diphenylphosphinomethyl)phenylphosphine (PPP) and tris(diphenylphosphinomethyl)phosphine (PPPP), were synthesized. All the compounds under study, [AuM2(PPP)2](3+) (M = Au (1), Cu (2), Ag (3)), [M4(PPPP)2](4+) (M = Ag (4), Au (5)), [AuAg3(PPPP)2](4+) (6), and [Au2Cu2(PPPP)2(NCMe)4](4+) (7), were characterized crystallographically. The trinuclear clusters 1-3 contain a linear metal core, while in the isostructural tetranuclear complexes 4-6 the metal framework has a plane star-shaped arrangement.