Determination and assessment of elemental concentration in the atmospheric particulate matter: a comprehensive review.

The elemental concentrations of atmospheric particulate matter (PM) have a detrimental effect on human health in which some elemental species have carcinogenic nature. In India, significant variations have found in the practices adapted from sampling to analysis for the determination and assessment of the elemental concentration in PM. Therefore, Indian studies (2011-2020) on the related domain are summarized to impart consistency in the field and laboratory practices. Further, a comparative analysis with other countries has also been mentioned in the relevant sections to evaluate its likeness with Indian studies. To prepare this study, literature has been procured from reputed journals. Subsequently, each step from sampling to analysis has thoroughly discussed with quality assurance and control (QA/QC) compliance. In addition, a framework has been proposed that showed field and laboratory analysis in an organized manner. Consequently, this study will provide benefit to novice researcher and improve their understanding about the related subject. Also, it will assist other peoples/bodies in framing the necessary decisions to carry out this study.

Manganese complexes and manganese-based metal-organic frameworks as contrast agents in MRI and chemotherapeutics agents: Applications and prospects.

Manganese-based Metal-organic Frameworks (Mn-MOFs) represents a unique sub-class of MOFs with low toxicity, oxidative ability, and biocompatibility, which plays vital role in the application of this class of MOFs in medical field. Mn-MOFs show great potential in biomedical applications, and has been extensively studied as compared to other MOFs in transition metal series. They are important in medical applications because Mn(II) possess large electron spin number and longer electron relaxation time. They display fast water exchange rate and could be employed as a potential MRI contrast agent because of their strong targeting ability. Manganese complexes with different ligands also display prospective applications in area such as carrier for drug targeting in anti-tumor and antimicrobial therapy. In the review presented herewith, the application of Mn-based complexes and Mn-MOFs have been emphasized in the area such as imaging viz. MRI, multimodal imaging, antitumor activities such as chemodynamic therapy, photodynamic therapy, sonodynamic therapy and antimicrobial applications. Also, how rational designing and syntheses of targeted Mn-based complexes and Mn-MOFs can engender desired applications.

Acid-assisted hydrogenation of CO2 to methanol using Ru(II) and Rh(III) RAPTA-type catalysts under mild conditions.

A highly efficient homogeneous catalyst system for production of CH3OH from CO2 using single molecular defined ruthenium and rhodium RAPTA-type catalysts [Ru(η6-p-cymene)X2(PTA)] (X = I(1), Cl(2); PTA = 1,3,5-triaza-7-phosphaadamantane) and rhodium catalysts [Rh(η5-C5Me5)X2(PTA/PTA-BH3)] (X = Cl(3), H(4) and PTA-BH3, H(5)) developed in acidic media under mild conditions. A TON of 4752 is achieved using a [Ru(η6-p-cymene)I2(PTA)] catalyst which represents the first example of CO2 hydrogenation to CH3OH using single molecular defined Ru and Rh RAPTA-type catalysts.

Transition-metal complexes of group 12 with 1,1'-bis(phosphanyl)ferrocene ligands.

The syntheses of four new cadmium and zinc complexes with 1,1'-bis(phosphanyl)ferrocene ligands and their phosphine chalcogenide derivatives are reported. The complexes were characterized by elemental analyses and IR, 1H NMR, 31P NMR and electronic absorption spectroscopy. The crystal structures of dichlorido[1-diphenylphosphinoyl-1'-(di-tert-butylphosphanyl)ferrocene-κ2O,P]cadmium(II), [CdCl2{(C17H14OP)(C13H22P)Fe}] or CdCl2(κ2P,O-dppOdtbpf) (1), bis[µ-(tert-butyl)(1'-diphenylphosphinoylferrocen-1-yl)phosphinato-κ3O,O':O'']bis[chloridozinc(II)], [Zn2{(C9H13O2P)(C17H14OP)Fe}2Cl2] or [ZnOCl{κ2O,O'-Ph2POFcPO2(t-Bu)}]2 (2), 1,1'-bis(di-tert-butylthiophosphinoyl)ferrocene, [Fe(C13H22PS)2] or dtbpfS2 (3), and [1,1'-bis(dicyclohexylphosphanyl)ferrocene-κ2P,P'][chlorido/cyanido(0.25/1.75)]zinc(II), [Zn(CN)1.75Cl0.25{(C17H26P)2Fe}] or Zn(CN)2(κ2-dcpf) (4), were determined crystallographically. Compound 1 has tetrahedral geometry in which the CdII centre is coordinated by one dppOdtbpf ligand in a κ2-manner and by two Cl atoms, while compound 2 displays a centrosymmetric dimeric unit in which two oxide atoms bridge the two Zn atoms to generate an eight-membered ring. Compound 3 revealed a sandwich structure with both phosphane groups sulfurized. In compound 4, the ZnII atom adopts a tetrahedral geometry by coordinating to the 1,1'-bis(dicyclohexylphosphanyl)ferrocene ligand in a κ2-manner and to two cyanide ligands.

Copper(I) Complexes Containing PCP Ligand Catalyzed Hydrogenation of Carbon Dioxide to Formate under Ambient Conditions.

The five new copper(I) complexes [Cu2(µ-Cl)2(κ1-PCPt-Bu)] (1), [Cu2(µ-Br)2(κ1-PCPt-Bu)] (2), [Cu2(µ-I)2(κ1-PCPt-Bu)] (3), [Cu2(µ-CN)2(κ1-PCPt-Bu)] (4), and [Cu4(µ3-SCN)4(κ1-PCPt-Bu)2]·CH2Cl2 (5) bearing a 1,3-bis[(di-tert-butylphosphino)methyl]benzene ligand were synthesized and characterized spectroscopically, and the molecular structures of 1, 3, and 5 were determined by single-crystal X-ray diffraction techniques. Structural studies for 1 and 3 revealed their binuclear structures with Cu···Cu separations of 2.609(3) and 2.6359(19) Å, respectively. However, 5 has a tetranuclear cubane structure with an 18-electron configuration at each copper without any metal-metal bonds. The two copper centers in 1 and 3 are bonded to one bridging PCPt-Bu ligand in a κ1-manner and two bridging (pseudo)halido ligands in a µ2-bonding mode to generate a nonplanar Cu2(µ-X)2 framework. The four copper centers in 5 are at the vertices of a tetrahedron. Each copper center has pseudo-tetrahedral coordination provided by two bridging PCPt-Bu ligands in a κ1-manner and the four bridging thiocyanate groups in a µ3-manner. These complexes were used as catalysts for the hydrogenation of CO2 to formate in the presence of DBU as a base to produce valuable energy-rich chemicals, and therefore it is a promising, safe, and simple strategy to conduct reactions under ambient pressure at room temperature. Among all of the five copper(I) complex based catalysts, 3 displayed the best catalytic performance with turnover number (TON) values of 38-8700 in 12-48 h of reaction at 25-80 °C. The outstanding catalytic performance of [Cu2(µ-I)2(κ1-PCPt-Bu)] (3) makes it a potential candidate for realizing the large-scale production of formate by CO2 hydrogenation.

A highly active copper catalyst for the hydrogenation of carbon dioxide to formate under ambient conditions.

Carbon dioxide (CO2) is an important reactant and can be used for the syntheses of various types of industrially important chemicals. Hence, investigation concerning the conversion of CO2 into valuable energy-rich chemicals is an important and current topic in molecular catalysis. Recent research on molecular catalysts has led to improved rates for conversion of CO2 to energy-rich products such as formate, but the catalysts based on first-row transition metals are underdeveloped. Copper(i) complexes containing the 1,1'-bis(di-tert-butylphosphino) ferrocene ligand were found to promote the catalytic hydrogenation of CO2 to formate in the presence of DBU as the base, where the catalytic conversion of CO2via hydrogenation is achieved using in situ gaseous H2 (granulated tin metal and concentrated HCl) to produce valuable energy-rich chemicals, and therefore it is a promising, safe and simple strategy to conduct reactions under ambient pressure at room temperature. Towards this goal, we report an efficient copper(i) complex based catalyst [CuI(dtbpf)] to achieve ambient-pressure CO2 hydrogenation catalysis for generating the formate salt (HCO2-) with turnover number (TON) values of 326 to 1.065 × 105 in 12 to 48 h of reaction at 25 °C to 80 °C. The outstanding catalytic performance of [CuI(dtbpf)] makes it a potential candidate for realizing the large-scale production of formate by CO2 hydrogenation.

Design of Metal-Organic Frameworks for pH-Responsive Drug Delivery Application.

Metal-Organic Frameworks (MOFs) have aroused great interest in the field of nanoscience and nanotechnology particularly in biomedical domains, such as Drug Delivery System (DDS), Biomedical Imaging (BI) and Photodynamic Therapy (PDT). As an emerging material, MOFs possess extraordinarily high surface area, controllable particle size and good biocompatibility. With extraordinary flexibility in the selection of organic and inorganic components, MOFs can rationally be tuned to obtain the materials having versatile structures and porosities. MOFs can serve as ideal vehicles for DDS, BI and PDT through modification and function. In this review, we summarized the design and synthetic strategies for preparing MOFs and introduced their recent advanced usage in DDS, BI and PDT. Finally, the prospect and future challenges of these nanomaterials are also documented.

Photocatalytic and Ferric Ion Sensing Properties of a New Three-Dimensional Metal-Organic Framework Based on Cuboctahedral Secondary Building Units.

A new three-dimensional microporous metal-organic framework based on Zn(II) clusters with the formula {[Zn7(NDC)5.5(µ4-OH)3]·7DMF} n (1) (H2NDC = 1,4-naphthalenedicarboxylic acid) had been synthesized and characterized. The MOF 1 displays an uncommon bsn topology, which is based on a unique heptanuclear Zn7(OH)3(CO2)11 cluster as a secondary building unit. The MOF had been employed as a photocatalyst for the photodegradation of model organic dyes rhodamine B and methyl violet in light. The results of photocatalytic experiments showed that 1 can successfully be employed as the photocatalyst for the benign decomposition of these dyes. A mechanism for the photcatalysis exhibited by 1 had been proposed using the results of density of states (DOS) and partial DOS calculations. The fluorescence properties of the MOF have been investigated, which revealed that 1 could be exploited as the luminescent sensor to recognize Fe3+ ions with perceptible quenching (K sv = 6.55 × 104 M-1) and a limit of detection of 1.16 ppm.

Synthetic, spectral, structural and catalytic activity of infinite 3-D and 2-D copper(ii) coordination polymers for substrate size-dependent catalysis for CO2 conversion.

Two copper(ii) coordination polymers, viz. [Cu2(OAc)4(µ4-hmt)0.5]n (1) and [Cu{C6H4(COO-)2}2]n·2C9H14N3 (2), have been synthesized solvothermally and characterized. The solid-state structure reveals that 1 is an infinite three-dimensional (3D) motif with fused hexagonal rings consisting of Cu(ii) and hmt in a µ4-bridging mode, while 2 is an infinite two dimensional (2D) motif containing Pht-2 in a µ1-bridging mode. CP 1 has a two-fold interpenetrated diamondoid network composed of 4-connected sqc6 topology with the point symbol of {66}, while 2 has a Shubnikov tetragonal plane network possessing a 4-connected node with an sql topology with a point symbol of {44·.62}-VS [4·4·4·4·*·*]. Both CPs 1 and 2 serve as efficient catalysts for CO2-based chemical fixation. Moreover, 1 demonstrates one of the highest reported catalytic activity values (%yield) among Cu-based MOFs for the chemical fixation of CO2 with epoxides. 1 shows high efficiency for CO2 cycloaddition with small epoxides but its catalytic activity decreases sharply with the increase in the size of epoxide substrates. The catalytic results suggested that the copper(ii) motif-catalyzed CO2 cycloaddition of small substrates had been carried out within the framework, while large substrates could not enter into the framework for catalytic reactions. The high efficiency and size-dependent selectivity toward small epoxides on catalytic CO2 cycloaddition make 1 a promising heterogeneous catalyst for carbon fixation and it can be used as a recoverable stable heterogeneous catalyst without any loss of performance. The solvent-free synthesis of the cyclic carbonate from CO2 and an epoxide was monitored by in situ FT-IR spectroscopy and an exposed Lewis-acid metal site catalysis mechanism was proposed.

A New 3D 10-Connected Cd(II) Based MOF With Mixed Ligands: A Dual Photoluminescent Sensor for Nitroaroamatics and Ferric Ion.

The precise unification of functional groups and photoluminescence properties can give rise to MOFs that can offer diverse applications like selective detection of nitroaromatic compounds (NACs) which are considered to be an important ingredient of explosive as well as cation and anion sensing. Hence, a new 3D metal-organic framework (MOF) [Cd2(btc)(bib)(HCOO)(H2O)·H2O]n (1) has been synthesized using mixed ligand strategy by solvothermal reaction of cadmium acetate with two ligands viz. 1,3,5-benzenetricarboxylic acid (H3btc) and 1,4-bis(2-methyl-imidazol-1-yl)butane (bib). The MOF 1 possesses highly 10-connected network which is based on {Cd4(btc)2(bib)4} molecular building block. The studies showed that 1 could be taken as the fluorescent sensor for sensitive recognition of NACs, in particular 2,4,6-trinitrophenol (TNP) with notable quenching (K sv = 5.42 × 104 M-1) and LOD of 1.77 ppm. Additionally, 1 also displayed selective sensing for Fe3+ ions with K sv = 6.05 × 103 M- 1 and LOD = 1.56 ppm. Also, this dual sensor displayed excellent reusability toward the detection of TNP and Fe3+ ion. Theoretical calculations have been performed to propose the probable mechanism for the sensing luminescence intensity. Calculations indicated that because of the charge transfer and weak interaction that is operating between NACs and MOF, the weakening in the photoluminescence intensity resulted.

A ternary Fe(ii)-terpyridyl complex-based single platform for reversible multiple-ion recognition.

Multiple ion-recognition activity by a ternary Fe(ii)-terpyridyl complex, [Fe(PhT)(PT)]2+ (1) (PhT = 4'-phenyl-2,2':6',2''-terpyridine; PT = 4'-pyridyl-2,2':6',2''-terpyridine), is demonstrated for cyanide (CN-), fluoride (F-) and hydroxide (OH-) ions in an aqueous medium with sufficient sensitivity, fast response, reproducibility and selectivity with a dual optical read-out. The sensing event was reversible with the "by-eye" visualization of back and forth colour changes. Three cyanide ions replaced PT from 1, as observed from the crystal structure of the 1 + CN- couple. Fluoride and hydroxide ions appeared to show multivariate interactions with 1. Observed structural and spectral changes correlated well with theoretical calculations. A string of cations at quantitative levels (Ag+/Hg2+/Fe2+/Fe3+) was used to decouple the 1 + anion complex to yield 1, which enabled the recognition of these cations while permitting the reuse of 1 for at least five set-reset cycles.

The utilization of a stable 2D bilayer MOF for simultaneous study of luminescent and photocatalytic properties: experimental studies and theoretical analysis.

A new Pb(ii)-based 2D MOF comprising π-conjugated ligand 4'-(1H-tetrazol-5-yl)-[1,1'-biphenyl]-3,5-dicarboxylic acid (TZBPDC) and having the formula {[PbNa(TZBPDC)](H2O)(DMF)2} n (1) has been synthesized. Structural characterization of 1 indicates that the MOF has a 4-connected (4,4) motif. The photoluminescent investigation indicates that 1 can behave as potential luminescent sensor for the detection of nitroaromatic compounds (NACs), especially 2,4-dinitrophenol (2,4-DNP) and ferric ions, through the decrease in its luminescence intensity. Additionally, 1 also displays excellent capacity for the photodegradation of methylene orange (MO), which is a constituent of wastewater discharge. The most plausible mechanisms for the decrease in the luminescent intensity of 1 in the presence of different NACs have been explored though theoretical calculations, and the photocatalysis of 1 for organic dyes has been addressed using density of states (DOS) and partial DOS calculations.

1,1'-Bis(di-tert-butylphosphino)ferrocene copper(I) complex catalyzed C-H activation and carboxylation of terminal alkynes.

Four copper(i) complexes, [CuBr(dtbpf)] (1), [CuI(dtbpf)] (2), [Cu4(µ2-I)2(µ3-I)2(µ-dtbpf)2] (3) and [Cu6(µ3-I)6(µ-dtbpf)2]·2CH3CN (4), were prepared using CuX (X = Br, I) and 1,1'-bis(di-tert-butylphosphino)ferrocene (dtbpf). These complexes have been characterized by elemental analyses, IR, (1)H and (31)P NMR, ESI-MS and electronic absorption spectroscopy. Molecular structures of the complexes 2 and 4 were determined crystallographically. Complex 2 is the first monomeric isolated Cu(i) complex of dtbpf with the largest P-Cu-P bite angle (120.070(19)°) to date. Complex 4 shows a centrosymmetrical dimeric unit with two [Cu3(µ3-I)3] motifs bridged by two bidentate dtbpf ligands in the κ(1)-manner. Each [Cu3(µ3-I)3] motif unites to form a pyramid with one copper atom at the apex and one of the triangular faces capped by an iodine atom. All the complexes were found to be efficient catalysts for the conversion of terminal alkynes into propiolic acids with CO2. Owing to the excellent catalytic activity, the reactions proceeded at atmospheric pressure and ambient temperature (25 °C). The catalytic products were obtained in moderate to good yields (80-96%) by using complex loading to 2 mol%. To the best of our knowledge, this is the first example of an active ferrocenyl diphosphine Cu(i) catalyst for the carboxylation of terminal alkynes with CO2.

Synthesis, characterization and light harvesting properties of Sb(III) and Bi(III) ferrocenyl dithiocarbamate complexes.

New Sb(III) and Bi(III) ferrocenyl dithiocarbamate complexes viz. [Sb(FcCH2Bzdtc)3] (Sb) and [Bi(FcCH2Bzdtc)3] (Bi) (Fc=C5H5FeC5H4-; Bz=C6H5CH2-) have been synthesized and characterized by elemental analyses, IR, (1)H and (13)C NMR spectroscopies. The optical, electrochemical and photovoltaic properties of the synthesized complexes were investigated. The light harvesting properties of both of the compounds have been studied using these compounds as photosensitizers in TiO2-based DSSCs. The photovoltaic devices fabricated by Sb and Bi showed a maximum current conversion efficiency of 1.51% and 0.97%, respectively under 1.5 AM illumination (100 mW cm(-2)) and having incident photon to current efficiency (IPCE) of 38% and 31%, respectively. The reason for the higher efficiency of Sb is due its higher dye loading.

Syntheses, characterization, and structural studies of copper(I) complexes containing 1,1'-bis(di-tert-butylphosphino)ferrocene (dtbpf) and their application in palladium-catalyzed Sonogashira coupling of aryl halides.

Four copper(I) complexes [Cu4(µ3-Cl)4(µ-dtbpf)2] (1), [Cu6(µ3-Br)4(µ2-Br)2(µ-dtbpf)3] (2), [Cu4(µ2-I)2(µ3-I)2(µ-dtbpf)2] (2) and [Cu2(µ1-CN)2(κ(2)-dtbpf)2] (4) were prepared using CuX (X = Cl, Br, I, CN) and 1,1'-bis(di-tert-butylphosphino)ferrocene (dtbpf) in 2 : 1 molar ratio in DCM-MeOH (50 : 50 V/V) at room temperature. These complexes were characterized by elemental analyses, IR, (1)H and (31)P NMR, ESI(+)-MS and electronic absorption spectroscopy. Molecular structures of the complexes 1,2 and 3 were determined crystallographically. Complexes 1 and 3 are tetrameric Cu(I) pseudo-cubane like structures with a Cu4Cl4 core, and a stepped cubane-like structure with a Cu4I4 core, respectively, whereas complex 2 shows a trimeric copper(I) framework containing two [Cu3(µ3-Br)2(µ2-Br)] units that are bridged by three bidentate µ-dtbpf ligands. Each [Cu3(µ3-Br)2(µ2-Br)] unit forms a pyramid with one copper atom at the apex and one of the triangular faces capped by one bromine atom. All the complexes were found to be efficient catalysts for the Sonogashira reaction. The coupling products were obtained in moderate to good yields (58-99%) using Pd loadings of 0.2 mol% as well as complex loading of 0.1 mol%. The (31)P NMR studies show that all the complexes are unstable during the course of tandem catalytic reaction and the dtbpf ligand migrates from copper(I) to palladium(II), which promotes palladium Sonogashira cross-coupling of activated and non-activated aryl halides.

A fast and selective probe for monitoring Pd(2+) in aqueous medium via the dual-optical readout.

A ready-to-use coordinative probe has been outlined for the detection of Pd(2+) at parts-per-million (ppm) levels which potentially meets real-world-challenges through a simple synthetic route, water based-activity, fast response, by-eye visualization, regenerative-action, high selectivity and the dual-optical readout for precise quantification.

A thiocyanato-bridged copper(I) cubane complex and its application in palladium-catalyzed Sonogashira coupling of aryl halides.

Reaction of copper(I) thiocyanate with 1,1'-bis(di-tert-butylphosphino) ferrocene (dtbpf) in a 2:1 molar ratio in DCM-MeOH (50:50 V/V) afforded a tetranuclear copper(I) complex [Cu4(µ3-SCN)4(κ(1)-P,P-dtbpf)2] (1) with a cubane-like structure. Complex 1 was shown to be an efficient catalyst in comparison to CuI in the Sonogashira reaction. The coupling products were obtained in high yields by using Pd loadings of 0.2 mol% as well as complex-1 of 0.1 mol%.

Synthesis, characterization and light harvesting properties of nickel(II) diimine dithiolate complexes.

Four Ni(II) diimine dithiolato complexes viz. [Ni{(S2C2Ph2)(1,10-Phenanthroline)}] (2), [Ni{(S2C2Ph2)(3,3'-dicarboxy-2,2'-bipyridyl)}] (3), [Ni{(S2C2Ph2)(4,4'-dicarboxy-2,2'-bipyridyl)}] (4) [Ni{(S2C2Ph2)(2,2'-bipyridyl)}] (5) have been prepared from [Ni(S2C2Ph2)2] (1) and characterized by microanalyses, UV-Vis, IR, (1)H and (13)C NMR. Attempts have been made to explain the nature of charge transfer in these molecules through quantum chemical calculations. The light harvesting properties of all the compounds have been studied using these compounds as photosensitizers in TiO2-based DSSC. The change in position of anchoring group on diimine derivative leads to different structural, electronic and light harvesting properties about the Ni(II) diimine dithiolate dyes.

Application of π-extended ferrocene with varied anchoring groups as photosensitizers in TiO2-based dye-sensitized solar cells (DSSCs).

Two new compounds, FcCH=NC(6)H(4)COOH (1) and FcCH=NCH(2)CH(2)OH (2) (Fc=C(5)H(4)FeC(5)H(5)), have been synthesized and characterized by elemental analyses, IR and (1)H NMR spectroscopy, and ESI-MS. Attempt has been made to explain their quasi-reversible redox behavior evidenced by cyclic voltammetry using density functional theory (DFT) calculations. Light-harvesting properties of both the compounds and also the starting material, FcCHO (3), have been studied using these compounds as photosensitizers in TiO(2)-based dye-sensitized solar cells having either a propylene carbonate-based electrolyte or ionic liquid electrolyte, namely, 1-propyl-3-methyl imidazolium iodide (PMII). Long-term stability of the photocurrent output of the cell using compound 1 as photosensitizer has been monitored periodically over 1400 h.

catena-Poly[[(pyridine-κN)copper(II)]-µ(3)-pyridine-2,6-dicarboxylato-κO:O,N,O:O].

In the title compound, [Cu(C(7)H(3)NO(4))(C(5)H(5)N)](n), the Cu(II) atom is in a slightly distorted octa-hedral coordination environment. Each Cu(II) atom is bound to two N atoms and one O atom of the pyridine-dicarboxyl-ate (PDA) ligand in a tridentate manner, one N atom of the pyridine mol-ecule and two bridging carboxyl-ate O atoms of adjacent PDA ligands, leading to a linear one-dimensional chain running along the c axis. These chains are further assembled via weak C-H⋯O and π-π inter-actions into a three-dimensional supra-molecular network structure. The centroid-centroid distance between the π-π inter-acting pyridine rings is 3.9104 (13) Å. The two N atoms are trans to each other with respect to Cu.