Pyrazole Ligands Research Articles

Design, synthesis, crystal structure, antitumour and antimicrobial evaluation of a novel substituted pyrazole and its some metal complexes

Designed and synthesized a novel substituted pyrazole ligand and its four novel Mn(II), Co(II), Ni(II) and Cu(II) complexes. The ligand, ‘substituted pyrazole’ was characterized by using single crystal X-ray diffraction and various physico-chemical measurements like elemental analysis and UV–Vis, IR, 1H NMR and HRMS spectral techniques. All the metal complexes were characterized based on their molar conductance, elemental analysis, magnetic susceptibility data and various spectral assignments. Furthermore, the biological applications of the synthesized complexes have been evaluated, mainly their cytotoxic, antitumour, especially ascites and solid- anticancer and antimicrobial activities. Cu(II) complex has better cytotoxic ability with an IC50 value 46 µg/ml and its anticancer talent is scrutinized against Earlich’s Ascites Carcinoma (EAC) cell line induced ascites tumour and Dalton’s Lymphoma Ascites cell line induced solid tumour in mice. Additionally, all the metal complexes have substantial and promising antimicrobial skill against some selected gram positive- and negative bacteria.

New sulfonated perylene diimide pyrazolate ligands: a simple route toward n-type redox-active hybrid materials.

We report the synthesis and the in depth electrochemical study of two novel electron accepting sulfonated perylene diimide pyrazolate ligands. Bridging the sulfone moieties of the perylene core unexpectedly affected the optical and electronic properties as evidenced by spectroelectrochemical investigation. Notably, we achieved a significant lowering of the LUMO level to -4.83 eV, ranking the ligand among the best electron acceptors via a straightforward synthetic procedure. These ligands can be foreseen for the development of n-type functional materials.

Europium is Different: Solvent and Ligand Effects on Oxidation State Outcomes and C-F Activation in Reactions Between Europium Metal and Pentafluorophenylsilver.

Unique outcomes have emerged from the redox transmetallation/ protolysis (RTP) reactions of europium metal with [Ag(C6 F5 )(py)] (py=pyridine) and pyrazoles (RR'pzH). In pyridine, a solvent not normally used for RTP reactions, the products were mainly EuII complexes, [Eu(RR'pz)2 (py)4 ] (RR'pz=3,5-diphenylpyrazolate (Ph2 pz) 1; 3-(2-thienyl)-5-trifluoromethylpyrazolate (ttfpz) 2; 3-methyl-5-phenylpyrazolate (PhMepz) 3). However, use of 3,5-di-tert-butylpyrazole (tBu2 pzH) gave trivalent [Eu(tBu2 pz)3 (py)2 ] 4, whereas the bulkier N,N'-bis(2,6-difluorophenyl)formamidine (DFFormH) gave divalent [Eu(DFForm)2 (py)3 ] 5. In tetrahydrofuran (thf), the usual solvent for RTP reactions, C-F activation was observed for the first time with [Ag(C6 F5 )(py)] in such reactions. Thus trivalent [{Eu2 (Ph2 pz)4 (py)4 (thf)2 (μ-F)2 }{Eu2 (Ph2 pz)4 (py)2 (thf)4 (μ-F)2 }] (6), [Eu2 (ttfpz)4 (py)2 (dme)2 (μ-F)2 ] (7), [Eu2 (tBu2 pz)4 (dme)2 (μ-F)2 ] (8) were obtained from the appropriate pyrazoles, the last two after crystallization from 1,2-dimethoxyethane (dme). Surprisingly 3,5-dimethylpyrazole (Me2 pzH) gave the divalent cage [Eu6 (Me2 pz)10 (thf)6 (μ-F)2 ] (9). This has a compact ovoid core held together by bridging fluoride, thf, and pyrazolate ligands, the last including the rare μ4 -1η5 (N2 C3 ): 2η2 (N,N'): 3κ(N): 4κ(N') pyrazolate binding mode. With the bulky N,N'-bis(2,6-diisopropylphenyl)formamidine (DippFormH), which often favours C-F activation in RTP reactions, neither oxidation to EuIII nor C-F activation was observed and [Eu(DippForm)2 (thf)2 ] (10) was isolated. By contrast, Eu reacted with Bi(C6 F5 )3 and Ph2 pzH or tBu2 pzH in thf without C-F activation, to give [Eu(Ph2 pz)2 (thf)4 ] (11) and [Eu(tBu2 pz)3 (thf)2 ] (12) respectively, the oxidation state outcomes corresponding to that for use of [Ag(C6 F5 )(py)] in pyridine.

Synthesis and coordination to the coinage metals of a trimethylpyrazolyl substituted 3-arylacetylacetone

AbstractThe ligand 3-(4-(1,3,5-trimethyl-1H-pyrazol-4-yl)phenyl)acetylacetone (1) combines a Pearson hard O,O′ chelating acetylacetone donor with a softer pyrazole N donor bridged by a phenylene spacer. Deprotonation and coordination to CuIIleads to a square planar bis-acetylacetonato complex; interpreting the close proximity of an adjacent complex’s pyrazole moiety as anη2${{\eta}}^{2}$coordination to the axial CuIIposition leads to a two dimensional extended structure. The N donor capabilities are proven by coordination to AgPF6and AuCl; for AgIa cationic linear bis-pyrazole complex as a toluene solvate is obtained with toluene-pyrazole π-interactions and an essentially uncoordinatedPF6-${{\mathrm{PF}}_{6}}^{-}$anion. In the case of AuCl a neutral linear coordination compound with one chlorido and one pyrazole ligand1is obtained. Comparing the dihedral angles with a closely related but shorter ligand reveals a larger rotational degree of freedom in1, allowing for richer architectures in emerging coordination polymers.

A Synthetic Route to a Ruthenium Complex via Successive Photosubstitution Reactions.

Photosubstitution reactions of cis-[Ru(bpy)2(MeCN)2]2+ with a pyrazole ligand (pzH) were studied under various conditions toward the development of a photochemical synthetic route to polypyridyl ruthenium complexes (bpy = 2,2'-bipyridine). In the absence of a base, light irradiation of an acetonitrile solution of pyrazole and cis-[Ru(bpy)2(MeCN)2]2+ gave a mixture of the reactant and cis-[Ru(bpy)2(pzH)(MeCN)]2+. In the presence of a mild base such as N,N-dimethylaminopyridine, a second photosubstitution from cis-[Ru(bpy)2(pzH)(MeCN)]2+ to cis-[Ru(bpy)2(pz)(pzH)]+ (1b) was greatly enhanced, as confirmed by UV-vis and 1H nuclear magnetic resonance spectroscopy. The yields of 1b were increased in solvents with moderate coordinating properties, such as acetone. The successive photosubstitution reaction was observed using a stoichiometric amount of pyrazole.

Multireversible Redox Processes in a Self‐Assembled Nickel Pentanuclear Bis(Triple‐stranded Helicate): Structural and Spectroscopic Characterizations in the NiII5 and NiINiII4 Redox States

AbstractWe previously reported the multireversible redox behavior of bis(triple‐helicate) pentanuclear complexes of the type [{M(μ‐bpp)3}2M(μ3‐X)]n+ (M=Mn, Fe with X=O and Co with X=OH) with rigid tetradentate binucleating 3,5‐bis(pyridine‐2‐yl)pyrazole (bpp−) ligand. In this article, we focus on the nickel derivative of this family, [{NiII(μ‐bpp)3}2NiII3(μ‐OH)]3+ (13+), which exhibits up to five reversible or quasi‐reversible one‐electron waves in CH3CN solution. The two one‐electron oxidized species as well as the one‐electron reduced species with respective compositions of 4NiII1NiIII (14+), 3NiII2NiIII (15+) and 1NiI4NiII (12+), were quantitatively generated by bulk electrolyses and spectroscopically characterized highlighting the high stability of this family of complexes in several redox states. In addition to the initial complex 13+, the mixed‐valence 12+ was also successfully characterized by single‐crystal X‐ray diffraction, allowing to locate the sites of successive reversible one‐electron events. 12+ is an unusual example of a multinuclear complex including the low‐valent Ni(I) state.

Chemically Stable Metal-Organic Frameworks: Rational Construction and Application Expansion.

Metal-organic frameworks (MOFs) have been attracting tremendous attention owing to their great structural diversity and functional tunability. Despite numerous inherent merits and big progress in the fundamental research (synthesizing new compounds, discovering new structures, testing associated properties, etc.), poor chemical stability of most MOFs severely hinders their involvement in practical applications, which is the final goal for developing new materials. Therefore, constructing new stable MOFs or stabilizing extant labile MOFs is quite important. As with them, some "potential" applications would come true and a lot of new applications under harsh conditions can be explored. Efficient strategies are being pursued to solve the stability problem of MOFs and thereby achieve and expand their applications.In this Account, we summarize the research advance in the design and synthesis of chemically stable MOFs, particularly those stable in acidic, basic, and aqueous systems, as well as in the exploration of their applications in several expanding fields of environment, energy, and food safety, which have been dedicated in our lab over the past decade. The strategies for accessing stable MOFs can be classified into: (a) assembling high-valent metals (hard acid, such as Zr4+, Al3+) with carboxylate ligands (hard base) for acid-stable MOFs; (b) combining low-valent metals (soft acid, such as Co2+, Ni2+) and azolate ligands (soft base, such as pyrazolate) for alkali-resistant MOFs; (c) enhancing the connectivity of the building unit; (d) contracting or rigidifying the ligand; (e) increasing the hydrophobicity of the framework; and (f) substituting liable building units with stable ones (such as metal metathesis) to obtain robust MOFs. In addition, other factors, including the geometry and symmetry of building units, framework-framework interaction, and so forth, have also been taken into account in the design and synthesis of stable MOFs. On the basis of these approaches, the stability of resulting MOFs under corresponding conditions has been remarkably enhanced.With high chemical stability achieved, the MOFs have found many new and significant applications, aiming at addressing global challenges related to environmental pollution, energy shortage, and food safety.A series of stable MOFs have been constructed for detecting and eliminating contaminations. Various fluorescent MOFs were rationally customized to be powerful platforms for sensing hazardous targets in food and water, such as dioxins, antibiotics, veterinary drugs, and heavy metal ions. Some hydrophobic MOFs even showed effective and specific capture of low-concentration volatile organic compounds.Novel MOFs with record-breaking acid/base/nucleophilic regent resistance have expanded their application scope under harsh conditions. BUT-8(Cr)A, as the most acid-stable MOF yet, showed reserved structural integrity in concentrated H2SO4 and recorded high proton conductivity; the most alkali-resistant MOF, PCN-601, retained crystallinity even in boiling saturated NaOH aqueous solution, and such base-stable MOFs composed of non-noble metal clusters and poly pyrazolate ligands also demonstrated great potential in heterogeneous catalysis in alkaline/nucleophilic systems for the first time.It is believed that this Account will provide valuable references on stable MOFs' construction as well as application expansion toward harsh conditions, thereby being helpful to promote MOF materials to step from fundamental research to practical applications.

Preparation, characterization, and structural studies of new ruthenium(II) and ruthenium(III) complexes incorporating pyrazole ligands

Multimetallic complexes containing disparate metals have been established to have practical utilities. We previously reported a strategy for preparing such species by using combinations of neutral pyrazole (Hpyz, C3N2H4) and anionic pyrazolyl ligands (pyz, C3N2H3–), and herein are reported several new complexes that should be capable of incorporating a second metal center. Two of the complexes, [Ru(1,5-cod)(Hpyz)3Cl][BPh4] and Ru(1,5-cod)(Hpyz)2(pyz)2 (cod = cyclooctadiene), were prepared from [Ru(cod)Cl2]2, while [Ru(tmeda)(Hpyz)2Cl2][BF4] (tmeda = tetramethylethylenediamine) was prepared from the neutral Ru(II) complex Ru(tmeda)(Hpyz)2Cl2 via one electron oxidation by the ferricinium ion. The first two complexes, one cationic and the other uncharged, involve Ru(II), while the tmeda complex involves Ru(III). All three species have been structurally characterized.

New mix-ligand copper(i) and copper(ii) pyrazolate complexes with 2,2′-bipyridine

The reaction of the trinuclear copper( i ) 3,5-bis(trifluoromethyl) pyrazolate with 2,2′-bipyridine on contact with air leads to the oxidation of Cu centers and affords trinuclear Cu ii complex containing bridged pyrazolate OH anions and chelating bipy ligands. Carrying out the reaction in the presence of dppm prevents oxidation and gives dinuclear copper( i ) complex with bridging dppm and pyrazolate ligands, and chelating bipy ligand. This complex exhibits red-orange phosphorescence originating from the 3MLbipyCT state.

Synthesis, Molecular Docking, MEP and SAR Analysis, ADME-Tox Predictions, and Antimicrobial Evaluation of Novel Mono- and Tetra-Alkylated Pyrazole and Triazole Ligands

Newly synthesized compounds of N-alkylated heterocyclic compounds were prepared by condensation of amine with alcohol which undergoes a reaction of SN2. These newly synthesized derivatives were characterized by spectral analysis. The objective is to prepare new potent nontoxic antimicrobial agents which are easy to synthesize and could be scaled up in pharmaceutical industries. Thirteen new heterocyclic compounds containing a pyrazole moiety were synthesized with good yields (29.79 to 99.6%) and were characterized by FTIR, 1H NMR, 13C NMR, and CG-MS techniques. The compounds were divided into two series—monoalkylated compounds (1–11) and tetra-alkylated compounds (12 and 13)—and then evaluated for their in vitro antifungal and antibacterial activities against several fungal and bacterial strains. None of the monoalkylated compounds had antibacterial or antifungal activity. However, the two tetra-alkylated pyrazole ligands displayed strong antibacterial potential. Moreover, compound 12 was more potent against all tested bacterial strains than compound 13. Interestingly, compounds 12 and 13 acted as weak antifungal agents against Saccharomyces cerevisiae. ADME-Tox studies suggested that compounds 12 and 13 exhibit better toxicity profiles than the commercial antibiotic streptomycin. MEP studies suggested that compounds 12 and 13 have the same charge locations but differ in their values which are due to the condensed geometry of compound 13 that make it more polarizable than compound 12. Of particular interest, these different MEPs were evident in ligand protein docking, suggesting that compound 12 has better affinity with MGL enzyme than compound 13. All these findings suggested that these novel compounds represent promising antibacterial lead compounds.

Synthesis and structural characterizations of Pd(II) complexes bearing the new hexahydropyrimidine and tetrahydropyrimidinium based bis(pyrazole) ligands with DFT studies

The one pot reaction between 1,3­-diaminopropane, 3,5-dimethylpyrazole and paraformaldehyde afforded 1,3­-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)hexahydropyrimidine 1 in an excellent yield. The reaction of 1 with one equivalent of N-bromosuccinimide in DME gave the oxidized product 2; the same reaction in the presence of 4 equivalents of NBS yielded the pyrazole ring brominated product. Treatment of 2 with NH4PF6 gave its PF6− salt 3. Conversely, its BF4− salt was obtained directly from the reaction of AgBF4 with 1. Treatment of 3 with palladium(II) precursors gave two monomeric trans chelated complexes containing acetate and chloride ions as their PF6− salts. Conversely, 1 reacts with palladium(II) source to give the dimeric 20-membered palladacycle. The monomeric complexes are rigid molecules, whereas the dimer complex is fluxional as shown by their 1H NMR spectra. From the low temperature NMR study of the dimer complex the broad signals in the room temperature NMR spectrum are attributed to the fast interconversion between its conformers. All compounds were characterized by both spectroscopic and X-ray methods, and in some cases by CHN analysis. DFT calculations were performed to understand the formation of the chelate complex against its anticipated NHC complex containing the 6-membered ring and the binuclear complex against a monomeric complex in terms of 5- and 6-membered ring strain energies.

Synthesis and biological evaluation of some new class of benzothiazole–pyrazole ligands containing arene ruthenium, rhodium and iridium complexes

Metal complexes 1–9 have been synthesized by reacting the benzothiazole–pyrazole derivative ligands (L1, L2 and L3) with the metal precursors of ruthenium (Ru), rhodium (Rh) and iridium (Ir). The complexes have been isolated as cationic mononuclear N ∩ N chelating metal complexes having the general formula as [(arene)M(κ2(N∩N)-L)Cl]PF6 where L = L1, L2 and L3, M = Ru, Rh and Ir, arene = p-cymene, Cp*. Structural studies revealed the mode of binding of the ligands to the metal centers is through the nitrogen atom of the benzothiazole ring and the pyrazole nitrogen atom forming a five-membered ring. All these complexes were characterized by various spectroscopic techniques as well as by XRD analysis. These complexes, as well as the ligands, have been investigated for antibacterial and antioxidant activity studies where only a few of the complexes exhibited antibacterial activity against Gram-positive bacterial strains, i.e., Staphylococcus aureus and Bacillus thuringiensis with complex 6 showing the highest bacterial inhibition toward Staphylococcus aureus and complexes 3, 4 and 6 showing the highest inhibition toward Bacillus thuringiensis. While for the antioxidant activity study, all the compounds showed profound antioxidant potency with complexes 6 and 9 showing more the 50% DRSA activity with reference to ascorbic acid (100%) taken as a reference. The antioxidant activity of the complexes is more pronounced as compared to their respective ligands alone. Benzothiazole–pyrazole derivative ligands upon complexation with the halide bridged metal precursors resulted in the formation of mononuclear N ∩ N chelating complexes. These complexes have been investigated for biological studies such as antibacterial and antioxidant studies, and they arrayed potential response against the bacterial strains under study as well as good antioxidant activity.

Synthesis, structures, and reactivities of six-membered C[sbnd]N chelate protic pyrazole complexes of iridium

The reaction of the bis(acetato)iridium complex [Cp*Ir(OAc)2] with an equimolar amount of 3-benzyl-5-alkylpyrazoles followed by addition of an excess of potassium chloride afforded the six-membered, C–N chelate protic pyrazole complexes [Cp*IrCl(R-LH)] (2a, R = Me; 2b, R = tBu; R-LH = C6H4CH2-C3N2H2R-5-κC,κN). The reaction of 2a with carbon monoxide led to the formation of the carbonyl complex [Cp*Ir(CO)(Me-LH)]Cl (3a) featuring a CO stretching wavenumber comparable with that of the five-membered chelate complex. Meanwhile, dehydrochlorination of the methylpyrazole complex 2a with potassium tert-butoxide in toluene resulted in uptake of adventitious water to give the hydroxido-bridged dinuclear complex [(Cp*Ir)2{μ-Me-LH···(Me-L)}(μ-OH)] (4a). In 2-propanol, the reaction caused hydrogen transfer from the solvent to yield the hydrido-bridged dinuclear complex [(Cp*Ir)2{μ-Me-LH···(Me-L)}(μ-H)] (6a). These dinuclear products could not be obtained from the more sterically-demanding complex 2b, but the intermediary coordinatively unsaturated pyrazolato species can be trapped from both 2a and 2b by triphenylphosphine to give the pyrazolato–phosphine complexes [Cp*Ir(PPh3)(R-L)] (5a and 5b) The detailed structures of 2a, 2b, 3a, 4a, and 5b bearing a folded six-membered C–N chelate pyrazole ligand have been determined by X-ray analysis. The chlorido complexes 2a and 2b also catalyzed transfer hydrogenation of acetophenone with 2-propanol at 50 °C.

Fluorescence, DNA Interaction and Cytotoxicity Studies of 4,5-Dihydro-1H-Pyrazol-1-Yl Moiety Based Os(IV) Compounds: Synthesis, Characterization and Biological Evaluation.

Osmium(IV) pyrazole compounds and ligands were synthesized and well characterised. Ligands were characterized by heteronuclear NMR spectroscopy (1H & 13C), elemental analysis, IR spectroscopy and liquid crystal mass spectroscopy. Os(IV) complexes were characterized by ESI-MS, ICP-OES, IR spectroscopy, conductance measurements, magnetic measurements and electronic spectroscopy. Binding of compounds with HS-DNA were evaluated using viscosity measurements, absorption titration, fluorescence quenching, and molecular docking, which show effective intercalation mode exhibited by compounds. Binding constant of Os(IV) complexes are found to be 8.1 to 9.2 × 104M-1. Bacteriostatic and cytotoxic activities were carried out to evaluate MIC, LC50, and IC50. The compounds have been undergone bacteriostatic screening using three sets of Gram+ve and two sets of Gram-ve bacteria. MIC of complexes are found to be 72.5-100μM, whereas that of ligands fall at about 122.5-150μM.. LC50 count of ligands fall in the range of 16.22-17.28μg/mL whereas that of complexes of Os(IV) fall in the range of 4.87-5.87μg/mL. IC50 of osmium compounds were evaluated using HCT-116 cell line. All the Os(IV) compounds show moderate IC50.

A robust Co(II)-organic framework for photocatalytic dye degradation and treatment effect on the neonatal sepsis

A stable Co(II)-based metal–organic framework (MOF) was constructed by applying a dual ligand strategy. The ultra-stable Co(II) MOF, [Co(H3tpb)(Hbtc)]n (1), was obtained by hydrothermal reaction of a novel trimer pyrazole ligand H3tpb and a classic carboxylic ligand H3btc (H3tpb = 1,3,5-tris (pyrazolyl) benzene, H3btc = 1,3,5-benzoic acid). In addition, complex 1 shows photocatalytic activity for the degradation of the dyes methylene blue (MB) and methyl orange (MO) under UV light. About 83.8% MB and 75.3% MO could be removed within 150 min. Serial experiments were performed to evaluate the biological activity of this compound in neonatal sepsis and explore its related mechanism. The results of the ELISA showed that the compound could reduce the releasing of the inflammatory cytokines in a dose-dependent manner. Besides, the compound could also reduce the relative expression levels of the gram-positive bacterial virulence. Simulations based on the molecular docking found that the complex could form multiple hydrogen bonds with several residues in the domain pocket.

Synthesis, characterization, and biological evaluation of new copper complexes of naphthyl pyrazole ligands.

Two naphthalene pyrazole ligands were synthesized using KOH/DMSO and Cu catalyst and characterized with FT-IR, ESI-MS, 1H, and 13C NMR spectroscopies. The crystal structures of 1-(2-methylnaphthalen-1-yl)-1H-pyrazole (MeNap-Pz) ligand have been determined with X-ray crystal structure analysis. Reaction of the ligands with Cu(NO3)2x3.5H2O gave two new complexes and characterized with magnetic susceptibility, molar conductance, FT-IR, LCMS-MS, ICP-OES, NMR, thermogravimetric analysis, and ESR spectra. The spectral data of the ligands are coordinated to the metal ion through the nitrogen atoms of the pyrazole ring. Consequently, it has been determined that [Cu(MeNap-Pz)2(NO3)]NO3.2H2O complex showed square planar geometry and [Cu(NapMe-Pz)2(NO3)2].H2O complex showed octahedral geometry. All compounds were screened for in vitro antibacterial activity and copper complexes have been shown to be effective on bacteria.

Selective binding of anions by rigidified nanojars: sulfate vs. carbonate.

Selective binding and transport of highly hydrophilic anions is ubiquitous in nature, as anion binding proteins can differentiate between similar anions with over a million-fold efficiency. While comparable selectivity has occasionally been achieved for certain anions using small, artificial receptors, the selective binding of certain anions, such as sulfate in the presence of carbonate, remains a very challenging task. Nanojars of the formula [anion⊂{Cu(OH)(pz)}n]2- (pz = pyrazolate; n = 27-33) are totally selective for either CO32- or SO42- over anions such as NO3-, ClO4-, BF4-, Cl-, Br- and I-, but cannot differentiate between the two. We hypothesized that rigidification of the nanojar outer shell by tethering pairs of pyrazole moieties together will restrict the possible orientations of the OH hydrogen-bond donor groups in the anion-binding cavity of nanojars, similarly to anion-binding proteins, and will lead to selectivity. Indeed, by using either homoleptic or heteroleptic nanojars of the general formula [anion⊂Cun(OH)n(L2-L6)y(pz)n-2y]2- (n = 26-31) based on a series of homologous ligands HpzCH2(CH2)xCH2pzH (x = 0-4; H2L2-H2L6), selectivity for carbonate (with L2 and with L4-L6/pz mixtures) or for sulfate (with L3) has been achieved. The synthesis of new ligands H2L3, H2L4 and H2L5, X-ray crystal structures of H2L4 and the tetrahydropyranyl-protected derivatives (THP)2L4 and (THP)2L5, synthesis and characterization by electrospray-ionization mass spectrometry (ESI-MS) of carbonate- and sulfate-nanojars derived from ligands H2L2-H2L6, as well as detailed selectivity studies for CO32-vs. SO42- using these novel nanojars are presented.

Volatile and thermally stable silver pyrazolate complexes containing N-heterocyclic carbene ligands

Treatment of [Ag((CF3)2pz)]3 or [Ag(tBu,C3F7)pz)]3 (pz = pyrazolate) with various stable N-heterocyclic carbenes (NHC) afforded silver(I) complexes containing pyrazolate and NHC ligands in 10–81% crystalline yields. These complexes were analyzed by spectral and analytical techniques and by X-ray crystal structure determinations. The solid state structures showed monomeric, dimeric, or tetrameric formulations, depending upon the pyrazolate and NHC substituents. To evaluate their potential as thin film growth precursors, [Ag((CF3)2pz)]3, [Ag(tBu,C3F7)pz)]3, and the new complexes were evaluated by thermogravimetric analyses, sublimation studies, thermal decomposition temperatures, and solution reduction experiments with potential reducing agents. The decomposition temperatures were higher for complexes containing (CF3)2pz ligands (203 to 293 °C) than for those containing (tBu,C3F7)pz ligands (160 to 200 °C). The complexes sublimed between 110 and 140 °C at 0.2 Torr. Solution reactions of several complexes with aqueous hydrazine, 1,1-dimethylhydrazine, formic acid, and tBuNH2 led to the formation of silver metal. Several of the new complexes have promising precursor properties for use in thin film growth by the atomic layer deposition and chemical vapor deposition techniques.

Synthesis, characterization and fluorescent properties of ferrocenyl pyrazole and triazole ligands and their palladium complexes

The search for new fluorescent materials with high quantum yields has been the focus of research, considering the diverse applications that fluorescent materials present. In this study, ferrocenyl pyrazolyl (L1) and ferrocenyl triazolyl (L2) ligands and their palladium metal complexes (1 and 2) were synthesized to investigate their fluorescence properties. While the pyrazolyl ligand was prepared through a ligand substitution reaction, synthesis of the triazolyl derivative involved the [3 + 2] azide-alkyne using click chemistry. All the prepared compounds have been characterized by NMR and IR spectroscopy, elemental analysis, mass spectrometry and single-crystal X-ray crystallography. These air-stable compounds were prepared in moderate to good yields (70% and 83%).The ferrocenyl-pyrazolyl L1 and ferrocenyl-triazolyl L2 ligands showed near-infrared (NIR) emission bands with quantum yields of 20% and 26% respectively. The addition of the Pd2+ ions results in the reduction of fluorescence intensity and quantum yield. Such fluorescent properties demonstrate their potential use in bio-analysis and as fluorogenic probing.

Rational Preparation of Atomically Precise Non-Alkyl Tin-Oxo Clusters with Theoretical to Experimental Insights into Electrocatalytic CO 2 Reduction Applications

Tin oxides (SnO2) have been widely utilized in electronics, nanolithography, and catalysis. As the atomically precise models of SnO2, tin-oxo clusters (TOCs) not only provide opportunities for mech...