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This study investigates post-synthetic ligand exchange in a series of copper(II) and chromium(II) cuboctahedral cages of the formula M24(R-bdc)24 through solvent-free mechanochemistry for the preparation of mixed-ligand cages. While solvent-based ligand exchange does not proceed when the cages are insoluble or when they are dissolved in non-coordinating solvents, solvent-free mechanochemistry can be used to prepare a number of mixed-ligand cages featuring a variety of functional groups regardless of cage solubility. We further extend this strategy to intercage ligand exchange reactions where the solid-state reaction of cages proceeds in just ten minutes while corresponding solvent-based reactions require more than one week of reaction time. The results highlight mechanochemically-facilitated ligand exchange as an exceptionally facile and efficient method for the production of mixed-ligand cuboctahedral cages. [ABSTRACT FROM AUTHOR]

The [(p-cymene)RuCl(κ²C,N-{CNHC-NH})]+X- (CNHC = thiazol-2-ylidene) complexes with a bidentate ligand (2: X = Cl and 3: X = PF6) were prepared by a one-pot reaction of vitamin B1 (VB1, 1), Ag2O and [(pcymene) RuCl2]2. In the complexes, VB1 coordinates through C2 and the exocyclic N in the imino form with the κ²-(C,N) coordination mode. The complexes 2 and 3 are stable in the solid state, but slowly release p-cymene in solution. Furthermore, upon heating in polar solvents, 2 or 3 can be converted by ligand exchange reactions to produce [(L)3RuCl(κ²C,N-{CNHC-NH})]+PF6- (4: L = py). Robustness was improved remarkably for 4. The complex 4 is stable in the solid state and in solution. The complexes 2-4 have been identified by ¹H and 13C{¹H} 2D NMR spectroscopy and 2 and 4 were studied by X-ray crystallography. In an effort to develop a recyclable catalyst in water, 2-4 were evaluated for TH of ketones and aldehydes with an azeotropic mixture of HCOOH/Et3N in water. The complexes 3 and 4 exhibited very good catalytic activity and 4 could be reused nine times without significant loss of activity, giving a high turnover frequency (TOF50%(h-1) = 1286). [ABSTRACT FROM AUTHOR]

Cumulenes and heterocumulenes with three or more cumulative multiple bonds are usually reactive species that serve as valuable building blocks for more complex molecules but tend to isomerize or cyclize and therefore are difficult to isolate. Using a mild ligand exchange reaction at the carbon in α‐metalated ylides, we have now succeeded in the synthesis and gram‐scale isolation of the elusive cyanoketenyl anion [NC3O]−. Despite its assumed cumulene‐like structure and the delocalization of the negative charge across the whole 5‐atom molecule, it features a bent geometry with a nucleophilic central carbon atom. Computational studies reveal an ambiguous bonding situation in the anion, which can be illustrated only by a combination of different resonance structures. Nonetheless, the anion features remarkable stability, thus allowing the storage of its potassium‐crown ether salt and its application as a highly functional synthetic building block. The cyanoketenyl anion readily reacts with a series of small molecules to form more complex organic compounds, including industrially valuable compounds such as cyanoacetate. This work demonstrated that reactive species can be generated by novel synthesis methods and open up atom‐economic pathways to complex compounds from small abundant molecules. [ABSTRACT FROM AUTHOR]

Cumulenes and heterocumulenes with three or more cumulative multiple bonds are usually reactive species that serve as valuable building blocks for more complex molecules but tend to isomerize or cyclize and therefore are difficult to isolate. Using a mild ligand exchange reaction at the carbon in α‐metalated ylides, we have now succeeded in the synthesis and gram‐scale isolation of the elusive cyanoketenyl anion [NC3O]−. Despite its assumed cumulene‐like structure and the delocalization of the negative charge across the whole 5‐atom molecule, it features a bent geometry with a nucleophilic central carbon atom. Computational studies reveal an ambiguous bonding situation in the anion, which can be illustrated only by a combination of different resonance structures. Nonetheless, the anion features remarkable stability, thus allowing the storage of its potassium‐crown ether salt and its application as a highly functional synthetic building block. The cyanoketenyl anion readily reacts with a series of small molecules to form more complex organic compounds, including industrially valuable compounds such as cyanoacetate. This work demonstrated that reactive species can be generated by novel synthesis methods and open up atom‐economic pathways to complex compounds from small abundant molecules. [ABSTRACT FROM AUTHOR]

Ligand‐exchange reactions on a mangana(II)cyclopentasilane complex that contains two THF ligands with aryl isocyanides led to the formation of manganese(0) bis(η2‐disilene) complexes via a retrocyclization. In stark contrast, ligand‐exchange reactions with CNtBu, an N‐heterocyclic carbene, or pyridine‐based ligands furnished manganese(II) complexes wherein the manganacyclopentasilane framework remained intact. The thermolysis of the obtained bis(η2‐disilene) complex in the presence of mesityl isocyanide led to the formation of a cyclotetrasilane via the formal dimerization of the two η2‐disilene moieties. The insertion of a mesityl isocyanide into the Mn−Siβ bond results in the formation of a manganese(II) complex supported by a [SiCSi]‐type tridentate ligand scaffold. [ABSTRACT FROM AUTHOR]

Ligand‐exchange reactions on a mangana(II)cyclopentasilane complex that contains two THF ligands with aryl isocyanides led to the formation of manganese(0) bis(η2‐disilene) complexes via a retrocyclization. In stark contrast, ligand‐exchange reactions with CNtBu, an N‐heterocyclic carbene, or pyridine‐based ligands furnished manganese(II) complexes wherein the manganacyclopentasilane framework remained intact. The thermolysis of the obtained bis(η2‐disilene) complex in the presence of mesityl isocyanide led to the formation of a cyclotetrasilane via the formal dimerization of the two η2‐disilene moieties. The insertion of a mesityl isocyanide into the Mn−Siβ bond results in the formation of a manganese(II) complex supported by a [SiCSi]‐type tridentate ligand scaffold. [ABSTRACT FROM AUTHOR]

A novel, repeatable, and swift kinetic approach for determining alpha-lipoic acid (ALA) in sodium lauryl sulfate (SLS) micellar medium has been presented, and it has been connected to ALA determination in drug formulations. The approach is based on ALA inhibitory property. ALA (containing two sulfur atoms) forms a chelate with Pd2+, lowering the effective [Pd(II)], and ultimately, the Pd2+ catalyzed cyanide substitution rate from [Ru(CN)6]4- by pyrazine (Pz). Fixed times of 5 and 10 minutes were chosen under optimal reaction conditions with [Pyrazine] = 3.0 × 10-4 mole L-1, pH = 4.0 ± 0.02, Temp = 318 ± 0.2 K, I = 0.1 mole L-1 (NaClO4), [Ru(CN)64-] = 2.75 × 10-5 mole L-1, [Pd+2] = 6.0 × 10-5 mole L-1, and [SLS] = 8.5 × 10-3 mole L-1 to calculate the absorbance at 370 nm associated with the final substitution product [Ru(CN)5 Pz]3-. ALA's inhibiting influence on the Pd2+ catalyzed cyanide substitution with pyrazine from [Ru(CN)6]4-, has been represented by a modified mechanistic approach. The concentration of ALA in various water specimens can be measured at the micro-level down to 1.25 × 10-6 mole L-1 using the established kinetic spectrophotometric approach. The suggested method is highly reproducible and has been effectively applied to accurately quantify the ALA in pharmaceutical samples. Even as much as 1000 with [ALA], typical additives used in medications do not significantly hinder the determination of ALA. [ABSTRACT FROM AUTHOR]

The coordination chemistries of transition metal complexes with pentagonal bipyramidal geometries were investigated, and the highly stable nature of a cyclic pentapyridyl ligand was disclosed. A NiCl2 complex with the pentapyridyl ligand was found to be stable toward water and acidic conditions. The stable complex underwent ligand‐exchange reactions with nucleophilic reagents, and a series of pentagonal bipyramidal complexes with different apical ligands was prepared. Crystallographic analyses with the aid of theoretical calculations revealed that the complexes were constructed by electrostatic threading of a divalent linear nickel complex into the ring of the neutral, cyclic pentapyridyl, which resulted in robust water‐ and acid‐resistant complexes with unique pentagonal bipyramidal structures. A reductive metal exchange reaction was then discovered, which enabled "linear divalent metal + electrostatic ring" formulations with different metal atoms. [ABSTRACT FROM AUTHOR]

Reactions of the technetium(I) nitrosyl complex [Tc(NO)(Cp)(PPh3)Cl] with triphenylphosphine chalcogenides EPPh3 (E = O, S, Se), and Ag(PF6) in a CH2Cl2/MeOH mixture (v/v, 2/1) result in an exchange of the chlorido ligand and the formation of [Tc(NO)(Cp)(PPh3)(EPPh3)](PF6) compounds. The cationic acetonitrile complex [Tc(NO)(Cp)(PPh3)(NCCH3)]+ is formed when the reaction is conducted in NCCH3 without additional ligands. During the isolation of the corresponding PF6− salt a gradual decomposition of the anion was detected in the solvent mixture applied. The yields and the purity of the product increase when the BF4− salt is used instead. The acetonitrile ligand is bound remarkably strongly to technetium and exchange reactions readily proceed only with strong donors, such as pyridine or ligands with 'soft' donor atoms, such as the thioether thioxane. Substitutions on the cyclopentadienyl ring do not significantly influence the ligand exchange behavior of the starting material. 99Tc NMR spectroscopy is a valuable tool for the evaluation of reactions of the complexes of the present study. The extremely large chemical shift range of this method allows the ready detection of corresponding ligand exchange reactions. The observed 99Tc chemical shifts depend on the donor properties of the ligands. DFT calculations support the discussions about the experimental results and provide explanations for some of the unusual findings. [ABSTRACT FROM AUTHOR]

Quantum‐chemical (DFT) calculations on hitherto unknown base(carbene)‐stabilized gallium monoiodides (LB→GaI) suggest that these systems feature one lone pair of electrons and a formally vacant p‐orbital – both centered at the central gallium atom – and exhibit metallomimetic behavior. The calculated reaction free energies as well as bond dissociation energies suggest that these LB→GaI systems are capable of forming stable donor‐acceptor complexes with group 13 trichlorides. Examination of the ligand exchange reactions with iron and nickel complexes indicates their potential use as ligands in transition metal chemistry. In addition, it is found that the title compounds are also able to activate various enthalpically robust bonds. Further, a detailed mechanistic investigation of these small molecule activation processes reveals the non‐innocent behavior of the carbene (base) moiety attached to the GaI fragment, thereby indicating the cooperative nature of these bond activation processes. The energy decomposition analysis (EDA) and activation strain model (ASM) of reactivity were also employed to quantitatively understand and rationalize the different activation processes. [ABSTRACT FROM AUTHOR]

For targeted therapy, the strategic use of an inactive precursor or "prodrug" could be an attractive strategy. Photo‐assisted chemotherapy offers a smart opportunity for developing new inorganic prodrugs for selective and temporal regulation on the chemotherapeutic activity of the prodrugs with light. The 3d transition metal complexes with versatile coordination number and geometry, redox, thermodynamic and kinetic properties, the presence of low‐energy metal‐centered electronic transitions, and the ability to exhibit light‐assisted chemical reactions have emerged as strategic tools for photo‐chemotherapeutic applications. Transition metal complexes are typically characterized by metal‐centered, ligand to metal, metal to ligand or intra‐ligand electronic transitions, and photo‐activated electronic states of the transition metal complexes potentially exhibit a wide range of chemical reactions viz. intramolecular oxido‐reduction reactions, intramolecular rearrangements, ligand exchange reactions or energy transfer those cascades into the generation of ROS (⋅OH, O2−⋅, O22−, 1O2), small molecules like H2, N2, CO or NO, and alkyl or aryl radicals. Applications of photo‐activable transition metal complexes for generating cytotoxic ions or radicals in the presence of light have emerged as an attractive strategy for photo‐activated chemotherapy (PACT). Here in, we reviewed the photophysical and photochemical aspects of the early transition metal complexes exhibiting photo‐ activated chemotherapy. [ABSTRACT FROM AUTHOR]

Atomically precise Au nanoclusters (NCs) with discrete energy levels can be used as photosensitizers for CO2 reduction. However, tight ligand capping of Au NCs hinders CO2 adsorption on its active sites. Here, a new hybrid material is obtained by anchoring of thiol functionalized terpyridine metal complexes (metal=Ru, Ni, Fe, Co) on Au NCs by ligand exchange reactions (LERs). The anchoring of Ru and Ni complexes on Au25 NC (Au25−Ru and Au25−Ni) leads to adequate CO2 to CO conversion for photocoupled electrocatalytic CO2 reduction (PECR) in terms of high selectivity, with Faradaic efficiency of CO (FECO) exceeding 90 % in a wide potential range, remarkable activity (CO production rate up to two times higher than that for pristine Au25PET18) and extremely large turnover frequencies (TOFs, 63012 h−1 at −0.97 V for Au25−Ru and 69989 h−1 at −1.07 V vs. RHE for Au25−Ni). Moreover, PECR stability test indicates the excellent long‐term stability of the modified NCs in contrast with pristine Au NCs. The present approach offers a novel strategy to enhance PECR activity and selectivity, as well as to improve the stability of Au NCs under light illumination, which paves the way for highly active and stable Au NCs catalysts. [ABSTRACT FROM AUTHOR]

Context: Rh(III) complexes demonstrated to exert promising pharmacological effects with potential applications as anti-cancer, anti-bacterial, and antimicrobial agents. One important Rh(III)-ligand is the pentamethylcyclopentadienyl (Cp*) group forming in water the [Cp*Rh(H2O)3]2+ complex. Among of its attractive chemical properties is the ability to react specifically with Tyr amino acid side chain of G-protein–coupled receptor (GPCR) peptides by means of highly chemoselective bioconjugation reaction, at room temperature and at pH 5–6. In this computational work, in order to deepen the mechanism of this chemoselective conjugation, we study the ligand exchange reaction between [Cp*Rh(H2O)3]2+ and three small molecules, namely p-cresol, 3-methylimidazole, and toluene, selected as mimetic of aromatic side chains of tyrosine (Tyr), tryptophan (Trp) and phenylalanine (Phe), respectively. Our outcomes suggest that the high selectivity for Tyr side chain might be related to OH group able to affect both thermodynamic and kinetic of ligand exchange reaction, due to its ability to act as both H bond acceptor and donor. These mechanistic aspects can be used to design new metal drugs containing the [Cp*Rh]2+ scaffold targeting specifically Tyr residues involved in biological/pathological processes such as phosphorylation by means of Tyr-kinase enzyme and protein–protein interactions. Methods: The geometry of three encounter complexes and product adducts were optimized at the B3LYP//CPCM/ωB97X-D level of theory, adopting the 6-311+G(d,p) basis set for all non-metal atoms and the LANL2DZ pseudopotential for the Rh atom. Meta-dynamics RMSD (MTD(RMSD)) calculations at GFN2-xTB level of theory were performed in NVT conditions at 298.15 K to investigate the bioconjugation reactions (simulation time: 100 ps; integration step 2.0; implicit solvent model: GBSA). The MTD(RMSD) simulation was performed in two replicates for each encounter complex. Final representative subsets of 100 structures for each run were gained with a sampling rate of 1 ps and analyzed by performing single point calculations using the FMO3 method at RI-MP2/6-311G//PCM[1] level of theory, adopting the MCP-TZP core potential for Rh atom. [ABSTRACT FROM AUTHOR]

Atomically precise Au nanoclusters (NCs) with discrete energy levels can be used as photosensitizers for CO2 reduction. However, tight ligand capping of Au NCs hinders CO2 adsorption on its active sites. Here, a new hybrid material is obtained by anchoring of thiol functionalized terpyridine metal complexes (metal=Ru, Ni, Fe, Co) on Au NCs by ligand exchange reactions (LERs). The anchoring of Ru and Ni complexes on Au25 NC (Au25−Ru and Au25−Ni) leads to adequate CO2 to CO conversion for photocoupled electrocatalytic CO2 reduction (PECR) in terms of high selectivity, with Faradaic efficiency of CO (FECO) exceeding 90 % in a wide potential range, remarkable activity (CO production rate up to two times higher than that for pristine Au25PET18) and extremely large turnover frequencies (TOFs, 63012 h−1 at −0.97 V for Au25−Ru and 69989 h−1 at −1.07 V vs. RHE for Au25−Ni). Moreover, PECR stability test indicates the excellent long‐term stability of the modified NCs in contrast with pristine Au NCs. The present approach offers a novel strategy to enhance PECR activity and selectivity, as well as to improve the stability of Au NCs under light illumination, which paves the way for highly active and stable Au NCs catalysts. [ABSTRACT FROM AUTHOR]

The versatile coordinating nature of N,S bidentate ligands is of great importance in medicinal chemistry imparting stability and enhancing biological properties of the metal complexes. Phenylthiocarbamide‐based N,S donor Schiff bases converted into RuII/OsII(cymene) complexes and characterized by spectroscopic techniques and elemental analysis. The hydrolytic stability of metal complexes to undergo metal‐halide ligand exchange reaction was confirmed both by the DFT and NMR experimentation. The ONIOM (QM/MM) study confirmed the histone protein targeting nature of aqua/hydroxido complex 2 aH with an excellent binding energy of −103.19 kcal/mol. The antiproliferative activity against a panel of cancer cells A549, MCF‐7, PC‐3, and HepG2 revealed that ruthenium complexes 1 a–3 a were more cytotoxic than osmium complexes and their respective ligands 1‐3 as well. Among these ruthenium cymene complex bearing sulfonamide moiety 2 a proved a strong cytotoxic agent and showed excellent correlation of cellular accumulation, lipophilicity, and drug‐likeness to the anticancer activity. Moreover, the favorable physiochemical properties such as bioavailability and gastrointestinal absorption of ligand 2 also supported the development of Ru complex 2 a as an orally active anticancer metallodrug. [ABSTRACT FROM AUTHOR]

The kinetics of the ligand exchange reaction between aquapentacyanoruthenate(II) [Ru(CN)5OH2]3− ion and naphthalene substituted ligands [α‐nitroso‐β‐naphthol (αNβN), and nitroso‐R‐salt (NRS)] has been studied in aqueous salt solutions of sodium chloride (NaCl) or tetrapropylammonium bromide (Pr4NBr) salt. The kinetics was monitored spectrophotometrically at 525 nm corresponding to the λmax of reddish‐brown‐colored substituted products, [Ru(CN)5(αNβN)]3− or [Ru(CN)5(NRS)]3−. Increasing the ionic strength of the reaction mixture using NaCl, exerted a negative salt effect on the rate of formation of naphthalene‐substituted products. At the same time, an increment in the concentration of Pr4NBr imparted a positive salt effect on the reaction. The observed rate constant (kobs) exhibits linear increment with respect to the concentration of NRS or αNβN while remaining invariant with variation in [Ru(CN)5OH2]3−. The computed activation parameters for NRS (∆H# = 24.55 kJ mol−1, Ea = 27.03 kJ mol−1, ∆G# = 87.83 kJ mol−1, and ∆S# = – 212.5 J K−1 mol−1) and αNβN ((∆H# = 17.33 kJ mol−1, Ea = 19.81 kJ mol−1, ∆G# = 87.87 kJ mol−1, and ∆S# = – 236.7 J K−1 mol−1) also support the proposed mechanism. [ABSTRACT FROM AUTHOR]

Cyclopentadienyl (Cp) Ru complexes exhibit diverse chemical reactivity and are versatile as catalysts, but their applications to functional materials are yet to be explored. To develop stimuli-responsive liquids based on their reactivity, Ru-containing ionic liquids (ILs) [Ru(Cp)L1L]Tf2N (L1 = N-hexyl-2-pyridinemethanimine; L = CO, MeCN, SMe2, and DMSO) were synthesized in this study. Their colors, physical properties, and chemical reactivities were dependent on the auxiliary ligand L, and these ILs exhibited interconversions via in situ ligand exchange. The exchange from CO to other ligands occurred via UV photoirradiation, whereas the other ligand exchange reactions occurred thermally. On the other hand, [Ru(Cp)L2(CO)]Tf2N (L2 = N-methyl-N-hexyl-2-pyridinemethanamine) did not undergo photochemical ligand exchange. [ABSTRACT FROM AUTHOR]

The design and research of luminescent and volatile organic compound (VOC) fluorescent sensing materials are of great significance and challenge. We report herein the ligand substitution reaction and VOC sensing of new heteroleptic [Cu(P˄P)N2]+ type copper(I) complexes. Firstly, three new complexes 1–3 were designed by utilizing a chelate diphosphine ligand 4,5‐bis(diphenylphosphino)‐9,9‐dimethylxanthene (Xantphos) and synthesized by the substitution reaction of different N‐containing ligands of 4‐PBO (1), 3‐PBO (2), and 4,4′‐Bipy (3) (4‐PBO = 2‐(4′‐pyridyl)‐benzoxazole, 3‐PBO = 2‐(3′‐pyridyl)‐benzoxazole, 4,4′‐Bipy = 4,4′‐bipyridine), respectively. Three complexes were characterized by elemental analysis, spectroscopic analysis (IR, UV–Vis), single‐crystal X‐ray diffraction (SCXRD), and photoluminescence study. The SCXRD study revealed that complexes 1 and 2 both exhibit a molecular structure with tetrahedral copper(I) complex cation and hexafluorophosphate anion, while complex 3 differs in that its cation is a binuclear copper(I) structure bridged by 4,4′‐bipyridine. Three complexes 1–3 present supramolecular ribbon, supramolecular dimer, and supramolecular framework structure, respectively. Some differences of their UV–Vis absorption spectra were explained by TD‐DFT calculation and wavefunction analysis. It is found that 1 has an abnormal luminescence blue shift, and a luminescence mechanism through the high‐energy T2 excited state is proposed by TD‐DFT calculation. Based on 3, a fluorescent test strip was developed, and its fast and selective fluorescent sensing of pyridine vapor through quenching mechanism was successfully realized. The fluorescent quenching mechanism of the material was also studied, and it was proposed that the quenching should be attributed to the photoinduced electron transfer (PET) mechanism. [ABSTRACT FROM AUTHOR]

BePhX1.91.9-0.3THFBePhX vs. Keywords: beryllium; Grignard compounds; ligand exchange; organometallics; Schlenk equilibrium EN beryllium Grignard compounds ligand exchange organometallics Schlenk equilibrium 1 13 13 10/31/23 20231026 NES 231026 B The reaction of homoleptic beryllium halide b with diphenyl beryllium complexes leads to the clean formation of heteroleptic beryllium I Grignard i compounds [(L) SB 1-2 sb BePh I X i ] SB 1-2 sb ( I X i =Cl, Br, I; L= I C i -, I N i -, I O i -donor ligand). BePhX7.12.91.7NEt3BePhX vs. [Extracted from the article]

Thermoplastic polymers obtained from resins such as Elium® combine desirable properties, including recyclability/reusability and excellent thermomechanical performances, at a relatively affordable cost. Nevertheless, their polymerization often requires a high amount of energy and/or involves hazardous chemical compounds. To address this last point, a series of bio-based captodative ligands was designed and synthesized in order to replace controversial phosphine oxides commonly used in low-energy initiating systems but suffering from toxicity issues. By using these captodative ligands, the curing time required for the polymerization of Elium® could be reduced from more than one hour to a mere 10 minutes. To gain a deeper insight into the redox mechanism involved during the polymerization process, the redox properties of a series of manganese(III) complexes containing different captodative ligands have been investigated employing cyclic voltammetry. It has been demonstrated that ligand exchange reactions induced by using the captodative (or push–pull) ligands possessing both electron-donating and electron-withdrawing groups had a significant impact on the reduction potential of the manganese(III) complexes. The reduction potential significantly changed depending on the type of heteroatom atom (X = O, S) and substituent included in the scaffold of the captodative ligands. [ABSTRACT FROM AUTHOR]

Keywords: hypervalent iodine; fluorination; fluorous; solid-supported synthesis; synthetic methodology; radiofluorination EN hypervalent iodine fluorination fluorous solid-supported synthesis synthetic methodology radiofluorination 2730 2736 7 08/17/23 20230901 NES 230901 Graph Advances in the synthesis of organofluorine compounds have led to major breakthroughs in the agrochemical, [1] pharmaceutical, [2] and organic materials [3] industries. Tosyloxy-benziodoxole 6a From B 4 b (139 mg, 0.5 mmol, 1.0 equiv), I p i -TsCl (95 mg, 0.55 mmol, 1.1 equiv) and Ag SB 2 sb CO SB 3 sb (138 mg, 0.25 mmol, 0.5 equiv) in CH SB 2 sb Cl SB 2 sb (2.5 mL). [10] Electrophilic radiofluorinations using N-F reagents [11] such as [ SP 18 sp F]NFSI [8] and [ SP 18 sp F]Selectfluor [9] have been reported, but these reagents ultimately derive from low specific activity of [ SP 18 sp F]F SB 2 sb , which translates to the ensuing radiotracer. [22] Mesyloxy-benziodoxole 6b From B 4 b (278 mg, 1.0 mmol, 1.0 equiv), MsCl (84 L, 1.1 mmol, 1.1 equiv) and Ag SB 2 sb CO SB 3 sb (276 mg, 0.50 mmol, 0.5 equiv) in CH SB 2 sb Cl SB 2 sb (5 mL). [Extracted from the article]

A simple, reproducible, and swift inhibitory kinetic approach for the N-acetylcysteine (NAC) determination has been developed and linked to NAC quantification in drug formulations. The method is based on the inhibitory feature of N-acetylcysteine. NAC forms a stable complex with Hg2+ and reduces the actual Hg2+ concentration and ultimately the rate of reaction between N-R-salt and [Ru(CN)6]4- catalyzed by Hg2+. Under the optimized experimental conditions with Temp = 45.0 ± 0.1°C, I = 0.05 mole dm-3 (KNO3), [N-R-salt] = 5.5 × 10-4 mole dm-3 [Hg+2] = 8.0 × 10-5 mole dm-3, pH = 6.0 ± 0.02, and [Ru(CN)64-] = 5.25× 10-5 mole dm-3, fixed time of 7 and 12 min was selected to compute the absorbance at 525 nm corresponding to the ultimate reaction product [Ru(CN)5 N-R-salt]3-. The inhibitory action of NAC toward cyanide imitation from [Ru(CN)6]4- by N-R-salt, catalyzed by Hg2+, has been demonstrated using a redesigned mechanistic scheme. With the proposed kinetic spectrophotometric method the micro-level quantification of NAC in distinct water samples can be done down to 1.25 × 10-6 mole dm-3. The developed procedure is highly reproducible and can be efficiently used to quantitatively estimate the NAC in the drug samples with high accuracy. The general additives present in drugs do not substantially interfere in the determination of NAC even up to 1000 times with [NAC]. [ABSTRACT FROM AUTHOR]

Rh(C2H4)2 species grafted on the HY zeolite framework significantly enhance the activation of H2 that reacts with C2H4 ligands to form C2H6. While in this case, the simultaneous activation of C2H4 and H2 and the reaction between these species on zeolite-loaded Rh cations is a legitimate hydrogenation pathway yielding C2H6, the results obtained for Rh(CO)(C2H4)/HY materials exposed to H2 convincingly show that the support-assisted C2H4 hydrogenation pathway also exists. This additional and previously unrecognized hydrogenation pathway couples with the conversion of C2H4 ligands on Rh sites and contributes significantly to the overall hydrogenation activity. This pathway does not require simultaneous activation of reactants on the same metal center and, therefore, is mechanistically different from hydrogenation chemistry exhibited by molecular organometallic complexes. We also demonstrate that the conversion of zeolite-supported Rh(CO)2 complexes into Rh(CO)(C2H4) species under ambient conditions is not a simple CO/C2H4 ligand exchange reaction on Rh sites, as this process also involves the conversion of C2H4 into C4 hydrocarbons, among which 1,3-butadiene is the main product formed with the initial selectivity exceeding 98% and the turnover frequency of 8.9 × 10−3 s−1. Thus, the primary role of zeolite-supported Rh species is not limited to the activation of H2, as these species significantly accelerate the formation of the C4 hydrocarbons from C2H4 even without the presence of H2 in the feed. Using periodic density functional theory calculations, we examined several catalytic pathways that can lead to the conversion of C2H4 into 1,3-butadiene over these materials and identified the reaction route via intermediate formation of rhodacyclopentane. [ABSTRACT FROM AUTHOR]

Polyaluminum cations, such as the MAl12 Keggin, undergo atomic substitutions at the heteroatom site (M), where nanoclusters with M = Al3+, Ga3+, and Ge4+ have been experimentally studied. The identity of the heteroatom M has been shown to influence the structural and electronic properties of the nanocluster and the kinetics of ligand exchange reactions. To date, only three ε-analogs have been identified, and there is a need for a predictive model to guide experiment to the discovery of new MAl12 species. Here, we present a density functional theory (DFT) and thermodynamics approach to predicting favorable heteroatom substitution reactions, alongside structural analyses on hypothetical ε-MAl12 nanocluster models. We delineate trends in energetics and geometry based on heteroatom cation properties, finding that Al3+–O bond lengths are related to heteroatom cation size, charge, and speciation. Our analyses also enable us to identify potentially isolable new ε-MAl12 species, such as FeAl127+. Based upon these results, we evaluated the Al3+/Zn2+/Cr3+ system and determined that substitution of Cr3+ is unfavorable in the heteroatom site but is preferred for Zn2+, in agreement with the experimental structures. Complimentary experimental studies resulted in the isolation of Cr3+-substituted δ-Keggin species where Cr3+ substitution occurs only in the octahedral positions. The isolated structures Na[AlO4Al9.6Cr2.4(OH)24(H2O)12](2,6-NDS)4(H2O)22 (δ-CrnAl13-n-1) and Na[AlO4Al9.5Cr2.5(OH)24(H2O)12](2,7-NDS)4(H2O)18.5 (δ-CrnAl13-n-2) are the first pieces of evidence of mixed Al3+/Cr3+ Keggin-type nanoclusters that prefer substitution at the octahedral sites. The δ-CrnAl13-n-2 structure also exhibits a unique placement of the bound Na+ cation, which may indicate that Cr3+ substitution can alter the surface reactivity of Keggin-type species. [ABSTRACT FROM AUTHOR]

Binary transition metal sulfides are considered to be a promising material for supercapacitors, possessing richer electrochemically active sites and superior electrochemical performance. Metal–organic frameworks (MOFs) are often used as self-sacrificing templates in the preparation of metal sulfides. Usually, direct sulfidation of MOFs tends to cause collapse of the morphological structure and blockage of the ion transport channels, so that the morphology of the original MOF template can be well preserved by using pyrolysis followed by S2− ion exchange. In this paper, we first prepared NiCo–MOF-74 on nickel foam by an in situ transformation method from layered double hydroxides (LDHs) through a ligand exchange reaction. Then, CoNi2S4 was synthesized in two steps involving the pyrolysis of NiCo–MOF-74 and a subsequent S2− ion exchange reaction. Compared with direct sulfidation, this synthetic strategy can well maintain the rod-like morphology of MOF-74 arrays and prevent structural collapse. The surface of CoNi2S4 has a fine nanosheet structure, which exposes more active sites and shows a high specific capacitance of 7.50 F cm−2 at 2 mA cm−2 and an excellent Coulomb efficiency (96.32%). In addition, the hybrid supercapacitor assembled with activated carbon shows a high energy density of 0.64 mW h cm−2 at a power density of 1.64 mW cm−2 and a high capacitance retention of 88.39% after 5000 cycles. These results indicate that rod-shaped CoNi2S4 can be controllably prepared from MOF-74 involving an exchange reaction and has promising application in high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Novel luminescent dialdiminate complexes of the Group 13 elements were prepared to evaluate the effects of the central element on their properties. We demonstrate that their absorption wavelength and the response to Lewis bases apparently depend on the central atom. The aluminum complex exhibited the absorption band in the higher‐energy region than the gallium and indium congeners. Theoretical calculations suggest that the aluminum complex has a lower‐lying highest‐occupied molecular orbital than the other complexes. Additionally, the emission intensity of the aluminum complex clearly changed in response to a Lewis base. Quantum chemical calculations suggest that these element‐dependent optical properties could originate from the difference in the electric charges on the central elements. Interestingly, the ligand exchange reactions were observed in the indium complexes together with the changes in the optical properties and controlled by the addition of InCl3 and InMe3. Furthermore, all the complexes showed aggregation‐induced emission enhancement (AIEE) and crystallization‐induced emission enhancement (CIEE) properties. These results lead to proposing a practical strategy for manipulating the optoelectronic properties coupled with the reactivities of complexes by choosing the central elements in the same group. [ABSTRACT FROM AUTHOR]

A brief review presents the results obtained by our research team in recent years on the structures (in the solid state and in solution), thermodynamics, stereoselectivity of the formation, and the kinetics of substitution reactions for a number of homo- and mixed-ligand complexes of some 3d elements with enantiomerically homogeneous and racemic forms of amino acids, natural di- and tripeptides, aromatic N-donors, new phosphorylated dithiocarbamates and hydrazone derivatives at different salt concentrations at several temperatures. Reliable results were obtained using spectroscopic methods, including spectrophotometry, EPR, and NMR relaxation, X-ray diffraction analysis, the stopped-flow method with spectrophotometric detection, and pH-metry in combination with mathematical modeling using a number of modern, including our own, programs. The structures of the complexes in solution were characterized by DFT quantum chemical calculations and molecular dynamics simulations. The key factors controlling the stereo-selectivity of the complex formation, the stability of complexes, and the kinetics of ligand substitution reactions were revealed. [ABSTRACT FROM AUTHOR]

Chemiluminescence (CL) has recently emerged as a novel light source for triggering various photoreactions with appealing features such as the elimination of continuous power supply and complex instrumentation. Here, CL‐induced cationic photopolymerization using ferrocenium salts as unimolecular photoinitiators is reported. The ferrocenium salts, facilely synthesized via ligand exchange reactions, absorb the visible light emitted from CL reactions and generate Lewis acids capable of initiating the cationic polymerization of oxirane and vinyl monomers. The presented method can be applied to create linear polymer chains and cross‐linked luminescent polymer networks, which have significant potential in the fabrication of new polymeric materials and various bioapplications. [ABSTRACT FROM AUTHOR]

This work applies organometallic routes to copper(0/I) nanoparticles and describes how to match ligand chemistries with different material compositions. The syntheses involve reacting an organo‐copper precursor, mesitylcopper(I) [CuMes]z (z=4, 5), at low temperatures and in organic solvents, with hydrogen, air or hydrogen sulfide to deliver Cu, Cu2O or Cu2S nanoparticles. Use of sub‐stoichiometric quantities of protonated ligand (pro‐ligand; 0.1–0.2 equivalents vs. [CuMes]z) allows saturation of surface coordination sites but avoids excess pro‐ligand contaminating the nanoparticle solutions. The pro‐ligands are nonanoic acid (HO2CR1), 2‐[2‐(2‐methoxyethoxy)ethoxy]acetic acid (HO2CR2) or di(thio)nonanoic acid, (HS2CR1), and are matched to the metallic, oxide or sulfide nanoparticles. Ligand exchange reactions reveal that copper(0) nanoparticles may be coordinated by carboxylate or di(thio)carboxylate ligands, but Cu2O is preferentially coordinated by carboxylate ligands and Cu2S by di(thio)carboxylate ligands. This work highlights the opportunities for organometallic routes to well‐defined nanoparticles and the need for appropriate ligand selection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Seven CuI hybrid micron phosphors with the emission from blue 450 nm to red 636 nm were sustainably synthesized via the aqueous PVP micelle-assisted assembly route. • The micron phosphors present excellent stability in water and can be dispersed in the aqueous solution of PVP or PVA to form homogenous luminescent inks. • The applications including anticounterfeiting, free-standing monochromatic and multichromatic emitting films and phosphors for LEDs were demonstrated. Low-cost and eco-friendly CuI hybrid compounds with various structures have recently attracted increasing attention due to their excellent optical properties and promising phosphor applications. However, the poor solubility and solution processability of bulk powders with agglomerated particle limited their practical applications greatly. In this work, we reported the self-assembly formation of CuI hybrid micron phosphors via the aqueous PVP micelle-assisted assembly route. Seven CuI hybrid micron phosphors with the emission from blue 450 nm to red 636 nm have been successfully synthesized. Among them, CuI-pyridine hybrid micron phosphors can be obtained via the reaction of CuI with various pyridines. PVP limits the size growth of the phosphors efficiently and it also plays an important role in controlling the distinct crystal phase formation. Whereas, micron phosphors based on bidentate ligands including 2-propylpyrazine, 5-bromopyrimidine or 4,4′-bipyridine need to be prepared via ligand exchange reaction. The micron phosphors present excellent stability in water and can be dispersed in the aqueous solution of PVP or PVA to form homogenous luminescent composites. The luminescent composites based on PVP are easy to use for fabricating anti-counterfeiting patterns via brush-painting or screen-printing. On the other hand, PVA composites can be applied for preparing free standing monochromatic or multichromatic emitting films as color convertor for display backlight. The PVA composites also exhibit the promising phosphor application for light-emitting diode (LED). Especially, the white LED can be directly realized via optimizing the mixing ratio of blue and orange phosphors. [ABSTRACT FROM AUTHOR]

Cu(I) 4H‐imidazolate complexes are rare examples of Cu(I) complexes with chelating anionic ligands and are potent photosensitizers with unique absorption and photoredox properties. In this contribution, five novel heteroleptic Cu(I) complexes with monodentate triphenylphosphine co‐ligands are investigated. As a consequence of the anionic 4H‐imidazolate ligand and in contrast to comparable complexes with neutral ligands, these complexes are more stable than their homoleptic bis(4H‐imidazolato)Cu(I) congeners. Here, the ligand exchange reactivity was studied by 31P‐,19F‐, and variable temperature NMR and the ground state structural and electronic properties by X‐ray diffraction, absorption spectroscopy, and cyclic voltammetry. The excited‐state dynamics were investigated by femto‐ and nanosecond transient absorption spectroscopy. The observed differences, with respect to chelating bisphosphine bearing congeners, are often due to the increased geometric flexibility of the triphenylphosphines. These observations render the investigated complexes interesting candidates for photo(redox)reactions not accessible with chelating bisphosphine ligands. [ABSTRACT FROM AUTHOR]

The synthesis and the crystal structure of the double cluster compound [Nb6Cl14(MeCN)4][Nb6Cl14(pyz)4]·6CH3CN are described. The synthesis is based on a partial ligand exchange reaction, which proceeds upon dissolving [Nb6Cl14(pyz)4]·2CH2Cl2 in acetonitrile. The compound is built up of two discrete neutral cluster units, which consist of octahedra of Nb6 atoms coordinated by 12 edge-bridging chlorido and two terminal chlorido ligands, and four acetonitrile ligands on one and four pyrazine ligands on the other cluster unit. Co-crystallized acetonitrile molecules are also present. The single-crystal structure determination has revealed a cluster arrangement in which the [Nb6Cl14(pyz)4] units are connected by (halogen) lone-pair–(pyrazine) π interactions. These lead to chains of [Nb6Cl14(pyz)4] clusters. These chains are further connected to cluster layers by (nitrile-halogen) dipole–dipole interactions, in which the [Nb6Cl14(MeCN)4] and co-crystallized MeCN molecules are also involved. These cluster layers are arranged parallel to the crystallographic {011} plane. [ABSTRACT FROM AUTHOR]

Ligand substitution reactions are common in solvated transition metal complexes, and harnessing them through initiation with light promises interesting practical applications, driving interest in new means of probing their mechanisms. Using a combination of time-resolved x-ray absorption spectroscopy and hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations and x-ray absorption near-edge spectroscopy calculations, we elucidate the mechanism of photoaquation in the model system iron(ii) hexacyanide, where UV excitation results in the exchange of a CN− ligand with a water molecule from the solvent. We take advantage of the high flux and stability of synchrotron x-rays to capture high precision x-ray absorption spectra that allow us to overcome the usual limitation of the relatively long x-ray pulses and extract the spectrum of the short-lived intermediate pentacoordinated species. Additionally, we determine its lifetime to be 19 (±5) ps. The QM/MM simulations support our experimental findings and explain the ∼20 ps time scale for aquation as involving interconversion between the square pyramidal (SP) and trigonal bipyramidal pentacoordinated geometries, with aquation being only active in the SP configuration. [ABSTRACT FROM AUTHOR]

Although multitargeted PtIV anticancer prodrugs have shown significant activities in reducing drug resistance, the types of bioactive ligands and drugs that can be conjugated to the Pt center remain limited to O‐donors. Herein, we report the synthesis of PtIV complexes bearing axial pyridines via ligand exchange reactions. Unexpectedly, the axial pyridines are quickly released after reduction, indicating their potential to be utilized as axial leaving groups. We further expand our synthetic approach to obtaining two multitargeted PtIV prodrugs containing bioactive pyridinyl ligands: a PARP inhibitor and an EGFR tyrosine kinase inhibitor; these conjugates exhibit great potential for overcoming drug resistance, and the latter conjugate inhibits the growth of Pt‐resistant tumor in vivo. This research adds to the array of synthetic methods for accessing PtIV prodrugs and significantly increases the types of bioactive axial ligands that can be conjugated to a PtIV center. [ABSTRACT FROM AUTHOR]

Although multitargeted PtIV anticancer prodrugs have shown significant activities in reducing drug resistance, the types of bioactive ligands and drugs that can be conjugated to the Pt center remain limited to O‐donors. Herein, we report the synthesis of PtIV complexes bearing axial pyridines via ligand exchange reactions. Unexpectedly, the axial pyridines are quickly released after reduction, indicating their potential to be utilized as axial leaving groups. We further expand our synthetic approach to obtaining two multitargeted PtIV prodrugs containing bioactive pyridinyl ligands: a PARP inhibitor and an EGFR tyrosine kinase inhibitor; these conjugates exhibit great potential for overcoming drug resistance, and the latter conjugate inhibits the growth of Pt‐resistant tumor in vivo. This research adds to the array of synthetic methods for accessing PtIV prodrugs and significantly increases the types of bioactive axial ligands that can be conjugated to a PtIV center. [ABSTRACT FROM AUTHOR]

The transition between digital and analog resistive switching in a single memristive device is beneficial for the reduction in power consumption and circuit complexity, the development of in‐memory neuromorphic computing, and the discovery of new switching mechanisms. However, achieving such transition is a challenge due to the complex switching mechanisms and device designs. Here, it is shown that the digital‐to‐analog resistive switching can be realized by the ligand exchange reaction of metal nanoparticles. The field‐injected copper cations migrate within carboxyl‐functionalized gold nanoparticle (AuNP) layer that are subsequently reduced into metallic filaments, enabling an abrupt resistive switching. Importantly, when the carboxyl groups on the gold nanoparticle are replaced by amino‐carboxyl ligands, the copper cations coordinate with the new ligands and create the conductance bridges to reduce the electron tunneling/hopping energy barriers, leading to continuous modulation in conductivity. This analog resistive switching allows to implement several important synaptic functions such as potentiation/depression, paired‐pulse facilitation, learning behaviors including forgetting curves and spaced learning effect. In the end, due to the non‐volatile characteristics, the gold nanoparticle synapse is used to build single layer perceptron for pattern classification with 100% accuracy. [ABSTRACT FROM AUTHOR]

Here, we report a switching method of singlet oxygen (1O2) generation based on the adsorption/desorption of porphyrins to gold nanoparticles driven by sulfide (thiol or disulfide) compounds. The generation of 1O2 by photosensitization is effectively suppressed by the gold nanoparticles and can be restored by a sulfide ligand exchange reaction. The on/off ratio of 1O2 quantum yield (ΦΔ) reached 7.4. By examining various incoming sulfide compounds, it was found that the ligand exchange reaction on the gold nanoparticle surface could be thermodynamically or kinetically controlled. The remaining gold nanoparticles in the system still suppress the generation of 1O2, which can be precipitated out simultaneously with porphyrin desorption by the proper polarity choice of the incoming sulfide to restore the 1O2 generation. [ABSTRACT FROM AUTHOR]

Crystal morphology of metal oxides in engineered metal-biochar composites governs the removal of phosphorus (P) from aqueous solutions. Up to our best knowledge, preparation of bio-assembled MgO-coated biochar and its application for the removal of P from solutions and kitchen waste fermentation liquids have not yet been studied. Therefore, in this study, a needle-like MgO particle coated tea waste biochar composite (MTC) was prepared through a novel biological assembly and template elimination process. The produced MTC was used as an adsorbent for removing P from a synthetic solution and real kitchen waste fermentation liquid. The maximum P sorption capacities of the MTC, deduced from the Langmuir model, were 58.80 mg g−1 from the solution at pH 7 and 192.8 mg g−1 from the fermentation liquid at pH 9. The increase of ionic strength (0–0.1 mol L−1 NaNO3) reduced P removal efficiency from 98.53% to 93.01% in the synthetic solution but had no significant impact on P removal from the fermentation liquid. Precipitation of MgHPO4 and Mg(H2PO4)2 (76.5%), ligand exchange (18.0%), and electrostatic attraction (5.5%) were the potential mechanisms for P sorption from the synthetic solution, while struvite formation (57.6%) and ligand exchange (42.2%) governed the sorption of P from the kitchen waste fermentation liquid. Compared to previously reported MgO-biochar composites, MTC had a lower P sorption capacity in phosphate solution but a higher P sorption capacity in fermentation liquid. Therefore, the studied MTC could be used as an effective candidate for the removal of P from aqueous environments, and especially from the fermentation liquids. In the future, it will be necessary to systematically compare the performance of metal-biochar composites with different metal oxide crystal morphology for P removal from different types of wastewater. Highlights: Bio-assembled MgO-coated biochar composite (MTC) was prepared and used for P sorption MTC removed 58.8 mg P g−1 from P solution and 192.8 mg P g−1 from fermentation liquid Precipitation and ligand exchange governed P sorption in solution Struvite formation and ligand exchange controlled P sorption in fermentation liquid MTC can be effectively used for P removal from the fermentation liquids [ABSTRACT FROM AUTHOR]

A biphasic [Mn(dipya)(H2O)4](tpht)/{[Zn(dipya)(tpht)]·H2O}n complex material, I (dipya = 2,2'-dipyridylamine, tpht2- = dianion of terephthalatic acid) was synthesized by ligand exchange reaction and characterized by XRPD and FTIR spectroscopy. A ZnO/ZnMn2O4 composite, II, has been prepared via thermal decomposition of I in an air atmosphere at 450 °C. XRPD, FTIR and FESEM analyses of II revealed the simultaneous presence of spherical nanoparticles of wurtzite ZnO and elongated nanoparticles of spinel ZnMn2O4. The specific surface area of II was determined by the BET method, whereas the volume and average size of the mesopores were calculated in accordance with the BJH method. The measurements of the mean size, polydispersity index and zeta potential showed colloidal instability of II. Two band gap values of 2.4 and 3.3 eV were determined using UV-Vis diffuse reflectance spectroscopy, while the measurements of photoluminescence revealed that II is active in the blue region of the visible spectrum. Testing of composite II as a pigmentary material showed that it can be used for the colouring of a ceramic glaze. [ABSTRACT FROM AUTHOR]

Metal ions play a very important role in nature and their homeostasis is crucial. A lot of metal-related chemical research activities are ongoing that concern metal-based drugs or tools, such as chelation therapy, metal- and metabolite sensors, metallo-drugs and prodrugs, PET and MRI imaging agents, etc. In most of these cases, the applied chelator/ligand (L) or metal–ligand complex (M–L) has at least to pass the blood plasma to reach the target. Hence it is exposed to several metal-binding proteins (mainly serum albumin and transferrin) and to all essential metal ions (zinc, copper, iron, etc.). This holds also for studies in cultured cells when fetal calf serum is used in the medium. There is a risk that the applied compound (L or M–L) in the serum is transformed into a different entity, due to trans-metallation and/or ligand exchange reactions. This depends on the thermodynamics and kinetics. For kinetically-labile complexes, the complex stability with all the ligands and all metal ions present in serum is decisive in evaluating the thermodynamic driving force towards a certain fate of the chelator or metal–ligand complex. To consider that, an integrative view is needed on the stability constants, by taking into account all the metal ions present and all the main proteins to which they are bound, as well as the non-occupied metal binding site in proteins. Only then, a realistic estimation of the complex stability, and hence its potential fate, can be done. This perspective aims to provide a simple approach to estimate the thermodynamic stability of labile metal–ligand complexes in a blood plasma/serum environment. It gives a guideline to obtain an estimation of the plasma and serum complex stability and metal selectivity starting from the chemical stability constants of metal–ligand complexes. Although of high importance, it does not focus on the more complex kinetic aspects of metal-transfer reactions. The perspective should help for a better design of such compounds, to perform test tube assays which are relevant to the conditions in the plasma/serum and to be aware of the importance of ternary complexes, kinetics and competition experiments. [ABSTRACT FROM AUTHOR]

Τhe Epidermal Growth Factor Receptor tyrosine kinase inhibitor (EGFR-TKI) 6-amino-4-[(3-bromophenyl) amino]quinazoline was derivatized with 6-bromohexanoyl-chloride and coupled with the tridentate chelating agents N-(2-pyridylmethyl) aminoethyl acetic acid (PAMA) and L(+)-cysteine bearing the donor atom set NNO and SNO, respectively. The rhenium precursors ReBr(CO)5 and fac-[NEt4]2[ReBr3(CO)3] were used for the preparation of the Re complexes fac-[Re(NNO)(CO)3] (5a) and fac-[Re(SNO)(CO)3] (7a) which were characterized by NMR and IR spectroscopies. Subsequently, the new potential EGFR inhibitors were labeled with the fac-[99mTc(CO)3]+ core in high yield and radiochemical purity (>90%) by ligand exchange reaction using the fac-[99mTc][Tc(OH2)3(CO)3]+ precursor. The radiolabeled complexes were characterized by comparative HPLC analysis with the analogous rhenium (Re) complexes as references. In vitro studies in the A431 cell lines showed that both ligands and Re complexes inhibit A431 cell growth. Complex 5a demonstrated the highest potency (IC50 = 8.85 ± 2.62 μM) and was further assessed for its capacity to inhibit EGFR autophosphorylation, presenting an IC50 value of 26.11 nM. Biodistribution studies of the 99mTc complexes in healthy mice showed high in vivo stability for both complexes and fast blood and soft tissue clearance with excretion occurring via the hepatobiliary system. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis and structural characterization of a series of new ruthenium(II) complexes 1–7, with the general formula mer-[RuL3(N–N)Cl]Cl, where L is 2,2′:6′,2′′-terpyridine (tpy) or 4′-(4-chlorophenyl)-2,2′:6′,2′′-terpyridine (Cl-Ph-tpy) and N–N is o-benzoquinonediimine (o-bqdi), 2,3-naphthoquinonediimine (nqdi), 4,4′-dimethyl-2,2′-bipyridine (dmbpy) or 2,2′-bipyridine-4,4′-dicarboxylic acid (dcbpy). The kinetic results showed that the ligand substitution reactions of new Ru(II)-polypyridyl complexes with biomolecules were affected by different substituents and the aromaticity of meridional tridentate and bidentate spectator ligands as well as by the nature of the entering nucleophile. The reactivity of the complexes increases in the order: dmbpy < dcbipy < nqdi < o-bqdi. In addition, quantum chemical calculations were performed to support the interpretation and discussion of the experimental data. Furthermore, combining ethidium bromide (EB) and Hoechst 33258 (2-(4-hydroxyphenyl)-5-[5-(4-methylpiperazine-1-yl)benzimidazo-2-yl]-benzimidazole) fluorescence assay results implied that 1–7 might interact with calf thymus DNA through partial intercalation and/or minor groove binding. The human serum albumin (HAS)-fluorescence binding studies involving the site markers, eosin Y, as a marker for site I of subdomain IIA, and ibuprofen, as a marker for site II of subdomain IIIA, showed that Ru(II) compounds bind to both sites with moderately strong affinity (Kb = 104–106 M−1). Moreover, these DNA/HSA experimental results were confirmed by molecular docking. Complexes 2, 5 and 6 exerted good to strong and highly selective cytotoxic activity against breast adenocarcinoma (MDA-MB 231), colorectal carcinoma (HCT116) and cervix adenocarcinoma (HeLa). Depending on their structure and cell line, the complexes acted differently in terms of their influence on autophagy, the cell cycle and the engaged apoptotic pathway. [ABSTRACT FROM AUTHOR]

Distribution of solvent molecules near transition‐metal complex is key information to comprehend the functionality, reactivity, and so forth. However, polarizable continuum solvent models still are the standard and conventional partner of molecular‐orbital (MO) calculations in the solution system including transition‐metal complex. In this study, we investigate the conformation, hydration, and ligand substitution reaction between NO2− and H2O in aqueous solution for [Ru(NO)(OH)(NO2)4]2− (A), [Ru(NO)(OH)(NO2)3(ONO)]2− (B), and [Ru(NO)(OH)(NO2)3(H2O)]− (C) using a combination method of MO theories and a state‐of‐the‐art molecular solvation technique (NI‐MC‐MOZ‐SCF). A dominant species is found in the complex B conformers and, as expected, different between the solvent models, which reveals that molecular solvation beyond continuum media treatment are required for a reliable description of solvation near transition‐metal complex. In the stability constant evaluation of ligand substitution reaction, an assumption that considers the direct association between the dissociated NO2− and complex C is useful to obtain a reliable stability constant. [ABSTRACT FROM AUTHOR]

The surface ligand environment plays a dominant role in determining the physicochemical, optical, and electronic properties of colloidal quantum dots (CQDs). Specifically, the ligand‐related electronic traps are the main reason for the carrier nonradiative recombination and the energetic losses in colloidal quantum dot solar cells (CQDSCs), which are usually solved with numerous advanced ligand exchange reactions. However, the synthesis process, as the essential initial step to control the surface ligand environment of CQDs, has lagged behind these post‐synthesis ligand exchange reactions. The current PbS CQDs synthesis tactic generally uses lead oxide (PbO) as lead precursor, and thus suffers from the water byproducts issue increasing the surface‐hydroxyl ligands and aggravating trap‐induced recombination in the PbS CQDSCs. Herein, an organic‐Pb precursor, lead (II) acetylacetonate (Pb(acac)2), is used instead of a PbO precursor to avoid the adverse impact of water byproducts. Consequently, the Pb(acac)2 precursor successfully optimizes the surface ligands of PbS CQDs by reducing the hydroxyl ligands and increasing the iodine ligands with trap‐passivation ability. Finally, the Pb(acac)2‐based CQDSCs possess remarkably reduced trap states and suppressed nonradiative recombination, generating a certified record Voc of 0.652 V and a champion power conversion efficiency (PCE) of 11.48% with long‐term stability in planar heterojunction‐structure CQDSCs. [ABSTRACT FROM AUTHOR]

Self-assembled coordination complexes prepared from a combination of Pd(II) components with one or more types of high-symmetry or low-symmetry bis/tris/tetrakis-monodentate ligands are considered in this review. The structures of these complexes are viewed in terms of the presence of a metallo-macromonocycle or conjoined metallo-macromonocycles/metallocages in the frameworks. Analysis of the typical molecular structures revealed an open truth that one or more units of metallo-macromonocycles can be conjoined to afford planar or non-planar systems. In the same line, the enveloping surface of a 3D cage can be considered as a multiple number of conjoined metallomacrocycles that embrace a 3D space from all directions. However, two or more units of cages are conjoined in a multi-3D-cavity cage system and such a system is considered as a conjoined cage. Construction of such conjoined cages having a finite but multiple number of 3D-cavities unified in a single molecular architecture is a challenging task when compared to that of single-3D-cavity based compounds. Conjoining of as many as four units of 3D cages is known so far. Single- as well as multi-cavity cages of lower symmetry have become a very recent trend in this regard where low-symmetry ligands or mixed ligand ensembles are crafted in the framework of the cages. Other structural diversities like helicity in cages, and supramolecular isomerism are also included in this assorted literature work. Although isomerism in classical coordination complexes is well known, it is very less studied in self-assembled coordination complexes. Ligand isomerism is one such feature that is reviewed here. The dynamic behavior of the cages results in interesting reactivity aspects. A large variety of dynamic processes are collected under an umbrella, i.e., "ligand exchange reactions" and described with examples. Intermolecular interaction among the already self-assembled molecules is possible in solution, solid, and gel-phases as discussed in the last part of this review. The understanding of intermolecular interaction is likely to influence different areas of research including crystal engineering, and materials chemistry. [ABSTRACT FROM AUTHOR]

A simple, reproducible, and rapid kinetic method for the S-Carboxymethyl-L-cysteine (CCys) determination has been proposed and linked to CCys quantification in pharmaceutical preparations. The method is based on the inhibitory feature of Carbocisteine. CCys forms a stable complex with Hg2+ and reduces the actual Hg2+ concentration and ultimately the rate of reaction between pyrazine (Pz) and [Ru(CN)6]4-catalyzed by Hg2+. Under the optimized reaction conditions with ionic strength (I) = 0.1 mol dm-3 (KCl), [Pyrazine (Pz)] = 3.0 × 10-4 mol dm-3, pH = 4.0 ± 0.03, [Hg+2] = 1.5 × 10-4 mol dm-3, [Ru(CN)64-] = 2.75 × 10-5 mol dm-3, and at 45.0 ± 0.2 o C temperature, fixed time of 9 and 14 min was selected to compute the absorbance at 370 nm corresponding to the ultimate reaction product [Fe(CN)5 Pz]3-. With the proposed kinetic spectrophotometric method, the micro-level quantification of CCys in distinct water samples can be done down to 1.25 × 10-6 mol dm-3. The developed procedure is highly reproducible and can be efficiently used to quantitatively estimate the CCys in the drug samples with high accuracy. The general additives present in drugs do not substantially interfere in the determination of CCys even up to 1000 times with [CCys]. [ABSTRACT FROM AUTHOR]

The organonickel σ-complex 2,3,4,5,6-pentamethylphenyl-nickel(II)-bromide-2,2′-bipyridine is synthesized electrochemically. This is the first example from a series of [NiBr(Aryl)(bpy)] complexes containing a meta-substituted aromatic moiety (Pmp is 2,3,4,5,6-pentamethylphenyl). The obtained compound is characterized in solution by 1H, 13С{1H}, and 1H13С{1H}–HSQC NMR and UV spectroscopy and ESI mass spectrometry. The crystal structure is determined by X-ray diffraction. The electrochemical properties of the complex are studied by cyclic voltammetry. It is found that in the DMF solution, a ligand exchange reaction occurs, resulting in the formation of a [Ni(Pmp)(bpy)(DMF)]+ derivative with elimination of the bromide anion. Similar cationic derivatives are active in catalytic processes of oligo- and polymerization of olefins, which indicates the importance of data obtained in this work for the development of the chemistry of nickel(II) organometallic complexes. [ABSTRACT FROM AUTHOR]

Hydrazones are common carbene precursors in many palladium-catalyzed cross coupling reactions of carbenes as a coupling partner, but their interaction with palladium has been overlooked. We have found that hydrazonato ligands readily coordinate to Pd aryl complexes leading to [PdAr(L–L){(TolSO2)N–N＝CHR}] (Ar = Ph, C6F5; L–L = dppe, dppf; R = CH＝CHPh, Ph). Ligand substitution reactions on [PdAr(dppe)X] (X = Br, TolSO2) show that the hydrazonato ligand coordinates preferentially so the hydrazonato complexes are likely resting states in catalytic carbene coupling reactions using hydrazones as reactants. The decomposition of the hydrazonato moiety to a diazoalkane is needed during the catalysis and the analysis of the evolution of the hydrazonato complexes shows that it is not promoted by coordination to the metal and it does not occur in the coordination sphere of palladium. The substitution of diazoalkane for the metal-bound hydrazonato is possible and the steps that follow to form a new C–C bond, including the carbene migratory insertion, are fast. [ABSTRACT FROM AUTHOR]

The paper presents innovative stochastic dynamic formulas treating quantitatively mass spectrometric outcome intensity by introducing diffusion coefficient, which is used to quantify and determine 3D structurally solvate inorganics of ZnII-ion observed under electrospray ionization conditions of metal-organics of 5-sulfosalicylic acid (1), 3,4-dihydroxy benzoic acid (2) and quinolin-8-ol (3), due to ligand exchange reactions of {[ZnII(H2O)6]2+)} and {[ZnIICl4]2-} counterions, determined by single crystal X-ray diffraction. The diffusion data are applied to multidimensional structural analysis using correlatively quantum chemical diffusion data according to Arrhenius's theory. We provide empirical proof of validity of a new simplistic derived equation D″SD = 2.6388.10−17 (–()2) to inorganics. The degree of testability of our formulas is justified by means of independent single crystal X-ray diffraction data. Insights into coordination chemistry of ZnII-ion in solution are gained. High accuracy quantum chemical static methods and molecular dynamics are utilized, as well. [ABSTRACT FROM AUTHOR]