Indium Complexes Research Articles

NMR spectroscopy of amino acid complexes of antimony(iii) and indium(iii) fluorides

The results of previously published NMR studies of amino acid complexes of antimony (iii) and indium(iii) fluorides are critically analyzed. Correlations between the NMR data, ion mobility, and structure of the complexes in question are considered. The interpretation of the low-temperature 19F NMR spectra of amino acid complexes of antimony(iii) fluorides is corrected and certain figures were changed for better informativity. Mechanisms of the onset of ion mobility in the studied complexes of Sb(iii) and In(iii) fluorides are proposed and the possibility of application of these compounds in the design of functional materials is assessed.

Antimicrobial Properties of Levofloxacin Antibiotic Complexes of Zirconium(IV) and Indium(III)

In this article, there are two new levofloxacin (HLevo) complexes were synthesized and spectroscopically discussed. These complexes were prepared in alkaline state (pH = 8) with the 1:1 stoichiometry between zirconyl(II) or indium(III) chloride and pure HLevo antibiotic drug ligand in mixed solvent equal volumes from methanol and bi-distilled water. The structures interpretation were performed based on the micro analytical (elemental analyses), molar conductance and spectroscopic measurements. It is shown that the deprotonated HLevochelate was coordinated towards ZrIV and InIII metal ions, this occurs as a bidentate ligand through the oxygen atoms of carboxylate and carbonyl group, respectively. Accordingly, these complexes can be speculated as [ZrO(Lev)(Cl)(H2O)] · H2O (1) and [In(Lev)(Cl)2(H2O)2] (2). Through Tranmission Electron Microscopy (TEM) imaging it is demonstrated that the nanoscale particles have a homogeneous distribution across the complex surface. Furthermore, by assessing in vitro antimicrobial activities, the inhibition activity of HLevo drug ligand as well as the associated metal ion complexes were evaluated towards specific types of bacteria and fungi.

Synthesis, characterization and photochemical properties of novel octakis(p–fluorophenoxy)substituted phthalocyanine and its gallium and indium complexes

Octakis(p-fluorophenoxy)-substituted phthalocyanine and its complexes of gallium and indium have been obtained in high yields (89% and 86% respectively). Unmetallated phthalocyanine and gallium complex were synthesized for the first time and the new method for the synthesis of indium complex was proposed. The obtained compounds were characterized by a combination of MALDI-TOF mass spectrometry, UV–Vis, and NMR spectroscopies. Photochemical properties of gallium and indium phthalocyanines were investigated. It was shown that these complexes maintained high production of singlet oxygen and potentially can be used in photodynamic therapy.

Synthesis and Photophysical Properties of (Cl2Ph)Salen‐based Indium Complexes

Herein, to elucidate the effect of substituent electronic properties on the photophysical properties of indium‐based organometallic luminophores, we prepare a series of indium complexes (1–5) with salen ligands bridged by an electron‐withdrawing 4,5‐dichlorophenylene (Cl2Ph) unit. The structures of all the complexes are fully confirmed by 1H and 13C NMR spectroscopy as well as elemental analysis. In particular, the molecular structure of 3, confirmed by X‐ray crystallography, is monomeric and the central indium atom adopts a square‐pyramidal geometry. The UV/Vis and fluorescence spectra of 1–5 show typically salen‐centered intramolecular charge transfer transitions with gradual bathochromic shifts as the electron‐donating ability of the substituents increases. This feature is further supported by electrochimical studies. Furthermore, the lowest unoccupied molecular orbital energy levels of 1–5 are considerably lower (approximately −3.70 eV) than those of salen‐based indium complexes with other aryl‐bridging units owing to the reduced electron‐donating effect of the (Cl2Ph)salen group.

Indium complex with task-specific ionic liquid ligands: Ligand to ligand charge transfer in the excited state investigation and reliable DFT predictions

The work describes the use of ionophilic indium complex bearing a task-specific ionic liquid as the ligand with hydrophilic chlorides. The new luminescent complex was designed to be completely water-soluble aiming at cell-imaging application. The indium derivative was also characterized by single-crystal X-ray analysis and the molecular arrangement could be compared in the condensed phase with aqueous solutions. An alternative methodology had to be employed to an accurate analysis of the photophysical properties determined by DFT calculations to describe the experimental results. The complex stabilizes from the excited state through a charge transfer process which was depicted as a ligand-to-ligand transfer (from a chlorine atom to the imidazolium ring) as indicated by the theoretical investigation. EPR experiments could be conducted at −196 °C to evaluate the charge transfer process and it proved to be in accordance with the predicted result from DFT calculations. The luminescent properties of the complex allowed it to be used as a bioprobe during cell-imaging experiments with several live cells lineages.

Synthesis of metal-free tetraazaisobacteriochlorin and via template condensation of phthalogenes

The indium(III) complexes of (4-(tert-butyl)phenyl)-substituted tetraazaisobacteriochlorin (TAiBC) and tetraazachlorin (TAC) were synthesized by direct template condensation of bis(4-(tert-butyl)phenyl)fumaronitrile and tetramethylsuccinonitrile using indium(III) ion as a matrix. The corresponding metal-free tetraazaisobacteriochlorin and tetraazachlorin were obtained by demetallation of their indium(III) complexes. These metal-free complexes were characterized using elemental analysis, mass-spectrometry, 1H and [Formula: see text]C{1H}NMR spectroscopy, UV-vis and MCD spectroscopy as well as DFT and TD-DFT calculations. Due to the low symmetry of the molecules, the NMR data were complex, but could be assigned by collecting 1D- and 2D NMR data and comparing with the results of quantum chemical calculations. From the position of the pyrrole proton signal (6.78 ppm), it was found that the diatropic current of TAiBC is much weaker than that of TAC, and plausibly the weakest among porphyrinoids so far reported. Absorption and MCD spectra were reasonably interpreted using the calculated absorption spectra.

Sonochemical synthesis and crystal structure of indium(III) complex as a modifier for electrochemical simultaneous determination of dopamine and acetylcholine

AbstractA novel mixed‐ligand complex of [In(Me‐phen)Cl3(DMSO)](1) was acquired and specified via spectral approaches (IR, UV–Vis, 1H‐NMR, and luminescence), thermal evaluation such as thermogravimetric, differential thermal analyses, and single‐crystal X‐ray diffraction. In this study, we have also reported the nanosize of [In(Me‐phen)Cl3(DMSO)](1) that has been synthesized via the sonochemical process. Characterization of nanoparticle(1) was carried out via X‐ray powder diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The sample size assembled via the sonochemical approach was approximately 20 nm. Also, a novel screen‐printed electrode modified with indium nanocomplex (In NC/SPE) was developed. An electrochemical examination of the adjusted electrode in addition to its efficiency in dopamine electro‐oxidation is explained. It was proven that dopamine oxidation at adjusted electrode surface takes place at 150 mV potential less positive compared to an unadjusted screen‐printed electrode. The relevant detection limit for dopamine was 2.0 × 10−7 M via differential pulse voltammetry. Moreover, the adjusted electrode was utilized to simultaneously determine dopamine and acetylcholine. Lastly, the adjusted electrode was utilized to determine dopamine and acetylcholine within real specimens.

Synthesis and structural characterization of methylindium imino/aminophenolates: Comparison to aluminum analogues and reactivity toward the coupling reactions of carbon dioxide with epoxides

We have synthesized methylindium complexes containing a variety of amino- and iminophenolate ligands for structural comparison to their aluminum analogues. The reaction of Me3In with the corresponding amino-/iminophenols resulted in the formation of MeIn(Et2NCH2CH2-abp) (1), MeIn(PyCH2-abp) (2), [MeIn(iPr-abp)]2 (3), MeIn(Ph-salen) (4), MeIn(Etsalan) (5), MeIn(Cy-ip) (6) and MeIn(Mes-ip) (7) [H2(Et2NCH2CH2-abp) = Et2NCH2CH2N(2-OH-3,5-C6H2tBu2)2, H2(PyCH2-abp) = (2-C5H4N)CH2N(2-OH-3,5- C6H2tBu2)2, H2(iPr-abp) = (CH3)2CHN(2-OH-3,5-C6H2tBu2)2, H2(Ph-salen) = 1,2-(NCH-2-OH-3,5-C6H2tBu2)2C6H4, H2(Et-salan) = 1,2-(NMeCH2-2-OH-3,5- C6H2tBu2)2C2H4, H(Cy-ip) = (2-OH-3,5-tBu2-C6H2)CHN(C6H11), and H(Mes-ip) = (2-OH-3,5-tBu2-C6H2CHN(2,4,6-Me3C6H2)]. X-ray crystallography studies show monomeric structures and five-coordinate indium centres for 1 and 2, a dimeric structure via intermolecular In⋯O interactions and fivecoordinate indium centres for 3, and monomeric structures and fourcoordinate indium centres for 6 and 7. DFT calculations were used to rationalize the observed dimeric structure of 3 and monomeric structures of 6 and 7, and gauge the effect of ligand steric bulk and atomic radius in indium versus aluminum on dimerization. Compounds 2 and 5 are active catalysts for coupling reactions of carbon dioxide and propylene oxide to yield propylene carbonate and carbon dioxide with cyclohexene oxide to yield polycyclohexene carbonate. This work provides insight into controlling intermolecular bonding and hence reactivity in indium and aluminum amino-/iminophenolate complexes, and represents one of the first examples of indium complexes as catalysts for the formation of cyclic- or polycarbonates from carbon dioxide and epoxides.

Stabilization of titanium(IV) and indium(III) complexes by coordination of [MoO3(1,4,7-triazacyclononane)] metalloligand in aqueous solution

A neutral weakly-donating [MoO3(tacn)] (tacn = 1,4,7-triazacyclononane) metalloligand has proved useful to stabilize Ti4+ or In3+ cation in aqueous solution. Thus, the reaction of [MoO3(tacn)] with TiOSO4 or In(NO3)3 in water affords a complex cation [Ti{MoO3(tacn)}6]4+ (1) or [In{MoO3(tacn)}6]3+ (2), respectively. The Ti4+ or In3+ cation is homoleptically coordinated by six [MoO3(tacn)] metalloligands. Each [MoO3(tacn)] coordinates Ti4+ or In3+ via one of its three oxygen atoms; the other two oxygens are hydrogen-bonded to NH groups of the neighboring [MoO3(tacn)]. These hydrogen bonding networks (i) strengthen [MoO3(tacn)] coordination to the Ti4+ or In3+ center and (ii) orient the six [MoO3(tacn)] units into two tripod-like arms that can catch a cation. One of the arms binds a tetramethylammonium cation through non-covalent CH···O bonds in 1 or a fac-{In(OH2)3}3+ cation through In–O coordination bonds in 2. Complex 1 dissolves intact in dry acetonitrile, as confirmed by 1H NMR spectroscopy and ESI-mass spectrometry. Addition of water or formamide to the acetonitrile solution disrupts the hydrogen bond networks and triggers dissociation of [MoO3(tacn)] from Ti4+, and importantly, the number of dissociated ligands can be managed by changing the amount of water or formamide. Therefore 1 is a prominent precursor for bottom-up synthesis of titanium–oxo clusters.

Absorption and emission properties of 5-phenyl tris(8-hydroxyquinolinato) M(III) complexes (M = Al, Ga, In) and correlations with molecular electrostatic potential.

Substituent effect for a series of 5-phenyl tris(8-hydroxyquinolinato) M(III) complexes (Mq3) of aluminum, gallium, and indium are investigated using density functional theory (DFT) for the ground state properties and the time-dependent version of DFT (TDDFT) for their absorption and emission properties. A comparison between the ground state energy of mer and fac isomers of all the complexes revealed that the mer configuration is always more stable than fac. The substituent effect is significantly reflected at the fluorescence maximum (λF ) values whereas the effect is moderate at the absorption maximum (λabs ) values. The molecular electrostatic potential (MESP) at the metal center (VM ) and the most electron rich region indicated by MESP minimum (Vmin ), located at the oxygen of phenoxide ring exhibit excellent correlations with the λF and Stokes shift (λF -λabs ) values. The study suggests the use of Stokes shift as an experimental quantity to measure the excited state substituent effect while the Vmin or VM emerge as theoretical quantities to measure the same.

Trigonal‐Bipyramidal vs. Octahedral Coordination in Indium(III) Complexes with Potentially S,N,S‐Tridentate Thiosemicarbazones

Three bis‐chelates of indium(III) with (partially fluorinated) S,N,S‐tridentate thiosemicarbazones (H2L) were prepared and their structures were studied in solution and in the solid state by NMR, ESI MS and single‐crystal X‐ray diffraction. The three compounds are isostructural in solution with five‐coordinate InIII ions and two differently coordinated thiosemicarbazonato ligands, [In(L)(HL)]. A temperature‐dependent 1H NMR study reflects the presence of dynamic processes in the molecules such as the resolution of hindered rotation around CN bonds with partial double‐bond character and the pH‐triggered isomerization between 5‐ and 6‐coordinate species. The latter is confirmed by the isolation of compounds with different solid‐state structures, [In(L)(HL)] and [In(L)2]–, depending on fluorine‐substitutions in the periphery of the thiosemicarbazones.

Indium complexes with aminothiolate ligands as single precursors for indium chalcogenides

Indium complexes with aminothiolate ligands, In(dmampS)2Cl (1) and In(dmampS)3 (2), were synthesized by the metathesis reaction of InCl3 with 2 equiv. and 3 equiv. of Li(dmampS), respectively. The reaction of 1 with 1 equiv. of KSeCN resulted in the formation of In(dmampS)2(NCSe) (3). The three complexes have been characterized by IR, NMR, Mass spectroscopy, and microanalysis. Single-crystal X-ray diffraction studies revealed that complexes 1 and 3 have distorted trigonal bipyramidal geometry at the indium center. Thermogravimetric analyses indicated that the residual materials of the complexes 1, 2, and 3 could be presumably In2S3, In2S3, and In2Se2S, respectively. Thermal decomposition of 1–3 formed In2S3 (for 1 and 2) and In2Se2S (for 3). This was confirmed using EDS and ICP-AES.

Structural, Topographical and Optoelectronic Properties of ZnIn2S4 Thin Films Deposited from Dual Source Using Aerosol Assisted Chemical Vapour Deposition (AACVD) Technique

The ZnIn2S4 (ZIS) thin films have been successfully developed from a homogeneous toluene solution of dithiocarbamate complexes of zinc and indium with formula [Zn(S2CNCy2)2(py)] (1) and [In(S2CNCy2)3].2py (2) via aerosol assisted chemical vapor deposition (AACVD) technique. Deposition experiments were carried out at 500oC in an inert atmosphere of argon gas on FTO substrate. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and Raman spectroscopy have been used for the determination of phase purity, surface topography of the uniformly distributed particles and oxidation states of the elements present in thin films. Further UV-visible spectrophotometry elucidates that the thin films absorbs in entire visible region and give estimated band gap energy of 2.37 eV. The photoelectrochemical (PEC) response in terms of linear scan voltammetry (LSV) provides a photocurrent density 2.27 mA.cm-2 at 0.7 V vs Ag/AgCl/3M KCl using 0.05 M sodium sulphide solution under AM 1.5 G illumination (100 mW.cm-2). The LSV results are further reinforced by electrochemical impedance spectroscopy (EIS) that gives charge transfer resistance (Rct) value of 5.7 x 104 Ω under dark conditions and reduces to 3.7 x 104 Ω under illumination.

Synthesis of a series of novel In(III) 2,6-diacetylpyridine bis(thiosemicarbazide) complexes: structure, anticancer function and mechanism.

The anticancer function and anticancer mechanism of indium (In) complexes still remain mysterious to date. Furthermore, it is greatly challenging to design a multi-functional metal agent that not only kills cancer cells but also inhibits their invasion and metastasis. Thus, to develop novel next-generation anticancer metal agents, we designed and synthesized a series of novel In(iii) 2,6-diacetylpyridine bis(thiosemicarbazide) complexes (C1-C4) for the first time and then investigated their structure-activity relationships with human urinary bladder cancer (T-24) cells. In particular, C4 not only showed higher cytotoxicity to cancer cells and less toxicity toward normal cells relative to cisplatin but also inhibited cell invasion and metastasis of T-24 cells. Interestingly, C4 acted against T-24 cells exhibiting multiple mechanisms: (1) arresting the S-phase of cell cycle via regulation of cytokine kinases, (2) activating the mitochondrial-mediated apoptosis, endoplasmic reticulum-stress-mediated cell death, PERK and c-Jun N-terminal kinase 1 (JNK) cell signaling pathways, and (3) inhibiting the expression of telomerase via the regulation of c-myc and h-TERT proteins. Our results suggested that C4 may be developed as a potential multi-functional and multi-targeting anticancer candidate.

Cationic indium catalysts for ring opening polymerization: tuning reactivity with hemilabile ligands.

This is a comprehensive study of the effects of rationally designed hemilabile ligands on the stability, reactivity, and change in catalytic behavior of indium complexes. We report cationic alkyl indium complexes supported by a family of hemi-salen type ligands bearing hemilabile thiophenyl (2a), furfuryl (2b) and pyridyl (2c) pendant donor arms. Shelf-life and stability of these complexes followed the trend 2a < 2b < 2c, showing direct correlation to the affinity of the pendant donor group to the indium center. Reactivity towards polymerization of epichlorohydrin and cyclohexene oxide followed the trend 2a > 2b > 2c with control of polymerization following an inverse relationship to reactivity. Surprisingly, 2c polymerized racemic lactide without an external initiator, likely through an alkyl-initiated coordination-insertion mechanism.

Synthesis and Photodynamic Activity of Vitamin-Chlorin Conjugates at Nanomolar Concentrations against Prostate Cancer Cells.

Phototoxicity response of synthesized vitamin–chlorin conjugates and their zinc and indium complexes was determined in the human PC-3 prostate cancer cell line, which was previously demonstrated to overexpress vitamin receptors on the cell surface. Pantothenic acid (Vit B5) and lipoic acid (or thioctic acid) were covalently linked to methyl pheophorbide (a chlorophyll derivative) and subsequently metallated with zinc and indium. Cell survival assay indicated that the vitamin–chlorin conjugates have better photodynamic activity against the PC-3 prostate cancer line at the nanomolar concentration range than the commercially available starting precursor methyl pheophorbide. Fluorescence and transmission electron microscopy studies indicated some formation of apoptotic cells and cytoplasmic vacuoles of photosensitized prostatic cells. Targeting vitamin receptors in prostatic cancer cells can be utilized to enhance specificity of photosensitizers for photodynamic therapy applications.

Acetophenone substituted phthalocyanines and their graphene quantum dots conjugates as photosensitizers for photodynamic antimicrobial chemotherapy against Staphylococcus aureus.

This work reports on the synthesis and characterization of novel acetophenone substituted phthalocyanines along with the self-assembled nanoconjugates formed via π-π stacking interaction between the synthesized unmetalated (2), zinc (3) and indium (4) phthalocyanines and graphene quantum dots (GQDs) to form 2@GQDs, 3@GQDs and 4@GQDs. The complexes and conjugates exhibited high singlet oxygen ranging from 0.20 to 0.79 in DMSO for Pcs and nanoconjugates where in all cases, the indium complexes showed the highest singlet oxygen quantum yields. The photodynamic antimicrobial chemotherapy activity of both phthalocyanines and nanoconjugates were tested against Staphylococcus aureus. 4@GQDs was found to be highly effective causing a 9.68 log reduction of the bacteria at 10 μM (based on Pc) when compared to 3.77 log reduction of 3@GQDs.

Highly Stable and Inert Complexation of Indium(III) by Reinforced Cyclam Dipicolinate and a Bifunctional Derivative for Bead Encoding in Mass Cytometry.

H2 cb-te2pa, a cross-bridged cyclam functionalized by two picolinate arms, was used for the formation of an incredible inert InIII chelate. The inertness of the complex was evaluated by UV/Vis experiments in several competitive media and was highlighted by the comparison with [In(dota)]- and [In(dtpa)]2- (H4 dota = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, H5 dtpa = diethylenetriamine pentaacetic acid), which are currently used in biological applications. For the first time, a bifunctional analogue of H2 cb-te2pa was prepared by C-functionalization to keep its coordination properties intact. However, this strategy leads to the formation of two diastereoisomers as evidenced and studied by NMR experiments and DFT calculations. Kinetic studies proved nevertheless that both isomers of the complex are equally inert. They were therefore used without distinction for their covalent grafting on polystyrene beads. The so-called metal-encoded beads were tested for imaging mass cytometry. The detection of 115 In allows the generation of images with high quality, proving the great potential of the bifunctional [In(cb-te2pa)]+ derivatives for single-cell analysis by mass cytometry.

Halide and Thiocyanate Metal Acid Complexes Extraction in the Water – Ethoxylated Nonylphenol – Ammonium Sulfate System

Nonionic ethoxylated surfactants, including ethoxylated nonylphenols, can be considered as neutral oxygen-containing extraction reagents, the formation of delamination systems with which is possible when salting-out with inorganic salts. In this work, the distribution of halide and thiocyanate acid complexes of thallium (III), iron (III), indium and gallium in the water – ethoxylated nonylphenol (neonol AF 9-12) – ammonium sulfate system at 25°C was investigated. It is established that thallium (III) is quantitatively extracted in the form of tetrahalidetallate-ion with an acidity of more than 0.1 mol/l, extraction of other metals is not quantitative. Among the thiocyanate acid complexes, zinc, cobalt and copper (II) are quantitatively concentrated, which can be used for group concentration of these metals or their extraction-spectrophotometric determination methods

Novel azaphthalocyanines with efficient anti-corrosion capability: Effect of halogens and heavy metals

A series of azaphthalocyanines (AzaPcs) substituted with peripheral 2,6-dihalogenated (Cl, Br or I) phenoxyl groups containing different central ions [2H+, Zn (II), Mg (II) or In (III)] were synthesized and their structural characterization were confirmed. Non-aggregation behavior exhibited by all the prepared complexes was perfectly achieved as confirmed by single crystal analyses due to the bulkiness of their peripheral substituents. Based on physicochemical analyses including fluorescence and singlet oxygen quantum yields, heavy metal effects were determined, and consequently, the highest singlet oxygen was recorded by the indium complex bearing iodine atoms (AzaPc12). The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) results revealed that the investigated azaphthalocyanine molecules pronouncedly retarded the mild steel corrosion in the acidic media by adsorbing at the metal/electrolyte interface. Theoretical DFT and molecular dynamic simulation studies supported the experimental results with the best inhibition efficiency achieved with AzaPc12. Surface morphology of mild-steel was examined by AFM and SEM techniques. The results proved the strong adsorption of AzaPc12 on the steel surface, forming a protective film which consistent with the electrochemical and theoretical results. The findings of this research obviously show a simple approach to the manufacture of phthalocyanine-derivatives that can find significant industrial application in metal corrosion suppression.