ABSTRACTIn this Comment, the content of the book by B.I. Kharisov, O.V. Kharissova, Carbon Allotropes: Metal-Complex Chemistry, Properties and Applications, published in 2019 by Springer Nature Publishing, has been characterized in detail. A great amount of information presented in this book is devoted to numerous varieties (allotropic modifications) of elemental carbon, each of which currently has not only purely academic, but also significant practical interest. This book is important for researchers working in the field of inorganic chemistry of carbon, as well as researchers in the field of chemistry of coordination compounds, which has traditionally been classified as inorganic chemistry since its inception.

ABSTRACT Based on the quantum-chemical calculation using the Density Functional Theory (DFT) method, the existence possibility of zinc heteroligand complexes with porphyrazine and its analogs – trans-di[benzo]porphyrazine or phthalocyanine and oxo ligands with an oxidation state of IV which is unknown for this element, was shown. The data on the structural parameters and multiplicity of the ground state of these complexes were presented. Graphical Abstract Comments on Inorganic Chemistry Volume ……., Issue ……., Pages ………. (2020). About of Possibility of Existence of Zn(IV) Oxidation State in Heteroligand Complexes with Porphyrazine, trans-Di[benzo]porphyrazine, Phthalocyanine and Oxo Ligands: Quantum-Chemical Review. Oleg V. Mikhailov, Denis V. Chachkov

ABSTRACTLuminescent metal-organic frameworks (LMOFs), as a subclass of MOFs, have attracted great attention, due to their promising potentials in practical applications. Therefore, as chemosensors, by combining the characteristic luminescent properties and the diversiform topological structures, LMOFs open up promising potentials for sensing. Nitroaromatic compounds (NACs) pose a great threat for environment and homeland security because of their toxicity and explosiveness, and then developing sensitive, selective, and reversible sensors for NACs is in great demand. In this review, we summarize recent works on LMOFs sensors for NACs through photophysical properties, sensing behaviors, possible mechanisms, existing problems and prospects for further developments.

ABSTRACTThis review analyses and discusses the methods, medium, matrix, and mechanisms of α-cyclodextrin (α-CD) based sensors reported in the literature. Small guest molecules are detected directly by the α-CD host molecule by capturing them in the cavity through host-guest complexation. Whereas big size species are detected by the probes tagged on the 1°/2° rim of the α-CD. i.e., on the exterior of the cavity. This is the first review report on the α-CD-based sensors.

(2022). Richard Hadley Holm: A Remembrance and A Tribute. Comments on Inorganic Chemistry: Vol. 42, No. 2, pp. 61-108.

ABSTRACTThis paper provides the sixth manifestation of a new tradition by which the editors of Comments on Inorganic Chemistry wish to lead by example, whereby we start publishing original research content that, nonetheless, preserves the Journal’s identity as a niche for critical discussion of contemporary literature in inorganic chemistry. (For the previous manifestations, see: Comments Inorg. Chem. 2018, 38, 1–35; 2019, 39, 1–26; 2019, 39, 188–215; 2020, 40, 1–24; 2020, 40, 277–303.) Coordination compounds are responsible for multiple quantum leaps in the performance of organic light-emitting diodes (OLEDs). The first breakthrough was via the green-fluorescent main-group complex tris-(8-hydroxyquinoline)aluminum (Alq3) which acts as both light-emitting and electron-transporting material in combination with triarylamine as a hole-transporter. To optimize the performance of such standard bilayer devices, herein we provide a double-doped structure into the emissive region consisting of 20 nm N,N’-diphenyl-N,N’-bis(1,1ʹ-biphenyl)-4,4ʹ-diamine (NPB) and 10 nm Alq3 utilized as buffer layers for facilitating charge injection from the electrodes, and a broad emissive region stacked by two doped layers with a 5% Alq3 doped in a 50-nm thick NPB layer – as well as a 5% NPB doped in a 40-nm-thick Alq3 layer from the anode side to the cathode side. The double-doped device achieves a decreased turn-on voltage of 2.44 V and maximum brightness of 17,300 cd/m2 as well as enhanced electroluminescence efficiency and moderately reduced efficiency roll-off over single-doped and standard bilayer devices. We have also found ~50% improvement of the photoluminescence quantum yield, with some subtle color shift upon doping 10% of NPB or Alq3 into the other vs. neat Alq3 (~0.3 vs. ~0.2 ϕPL) which nonetheless led only to ~20% improvement in EQE (~1.0% vs. ~0.8%), suggesting additional device optimization is warranted. Furthermore, two typical fluorescent OLEDs architectures – a graded or uniformly mixed device – have been exploited, which together with the double-doped approach would be feasible to boost EL efficiencies in both fluorescent and phosphorescent OLEDs with neat bilayer structures. The approach is not suitable for the more common doped phosphorescent devices, the optimization of which has been reviewed earlier by Nazeeruddin and coworkers in this Journal (Comments Inorg. Chem. 2017, 37, 117–145); in combination with this article, we hope that the reader will have an educational experience on OLED design and optimization from an inorganic chemistry perspective vis-à-vis a materials science perspective that dominates the OLED literature.

ABSTRACTA new recyclable and stable catalyst based on a Zr metal-organic framework, namely MIP-202 has been constructed through a simple post‐synthetic modification strategy as an extremely efficient and applied heterogeneous catalyst for Knoevenagel condensation reaction between benzaldehyde and ethyl cyanoacetate under mild reaction conditions. The principal purpose of this study is to reduce the amount of the protonated amine functional groups (NH3+) in the pores of MIP-202 using the solvent assisted ligand exchange (SALE), in order to achieve an optimal structure to obtain higher efficiencies in Knoevenagel condensation reaction. The resultant catalyst is characterized via various techniques including PXRD, FT-IR, FE-SEM, EDX, BET, AAS, CHN, and TG analyses. The post-modified catalyst exhibited high catalytic performance with 90% efficiency, which is an enhanced activity compared to the pristine MIP-202 MOF, and also four recycling stability without a significant decrease in catalytic activity. Therefore, it was proved that the adjustment of functional groups is an effective method for the improvement of the reaction process. The catalytic mechanism has also been investigated.

ABSTRACTLinear Free Energy Relationships (LFER) logKj = a⋅logKi between the stability constants (logK) of the Mn+L complexes of ith and jth metal ions Mn+ (Ca2+, Cd2+, Co2+, Cu2+, Fe2+, La3+, Mg2+, Mn2+, Ni2+, Pb2+, Th4+, VO2+, Y3+, Zn2+) with diverse organic ligands (L) in water were analyzed. From these 432 LFER it follows that each metal ion can be described by one parameter - thermodynamic ionic radius r, and the stability constants of two metal ions Mi and Mj with a ligand L are related by the simple relationship logKj = (ri/rj)logKi. Predictive performance of this relationship was tested on 228 metal ion pairs which were not used for the radii estimations, and the number of ligands varied from 20 to 221 for these metal ion pairs. Root mean squared error RMSE and squared determination coefficient Rdet2 of the logK predictions vary from 0.50 to 2.0 for 186 test sets and from 0.849 to 0.500 for 218 test sets, respectively.

ABSTRACTWith the emerging and alarming environmental deterioration and weakening of human health have become a global menace which have posed severe potential impact on the worldwide growing concern for the ecological conditions. Metal Organic Frameworks, a class of porous, robust and rigid compounds has been effectively fascinated and categorized for their versatile role as luminescent detectors and adsorbents for harmful anthropogenic pollutants from the environment . In this review, we aim to update the database of several MOFs which emphasize the role of MOFs, and their mechanism based on the luminescent detection and adsorptive removal of different anthropogenic pollutants. Moreover, we have tried a plausible way to relate these two applications to adapt the design, synthesis and experimental strategies of MOFs for simultaneous detection and adsorptive removal of anthropogenic contaminants.

ABSTRACTNanophotocatalysts have numerous applications in the field of water splitting, dissociation of volatile organic pollutants, organic synthesis, degradation of dyes/hazardous contaminants, cancer cells inactivation, self-cleaning surfaces, hydrogen evolution, photo-electrochemical conversion, etc. Typically, to produce nanophotocatalysts, diverse conventional physicochemical strategies have been reported with some important drawbacks/limitations such as the utilization of toxic/hazardous materials, complex/expensive instruments, and time-consuming reactions. Therefore, there is a high demand for developing green, environmentally friendly, and cost-effective synthetic tactics, which can reduce or eliminate the rigorousness and complications of the conventional approaches. These nanophotocatalysts have shown high stability, good recyclability, and remarkable catalytic activity. Typically, the significant specific surface areas, the abundant functional groups, large amounts of active sites are the important advantages of the nanoscaled structures for highly photocatalytic degradation of organic pollutants. However, more elaborative studies are still needed to overcome some important limitations/drawbacks of nanophotocatalysts for industrial applications, which include the difficult separation, low selectivity, aggregation/sedimentation, low-usage of visible light, fast charge recombination, and low migration potential of photo-generated electrons and holes. This review highlights recent advances related to the greener and eco-friendly synthesis of nanophotocatalysts, as well as their environmental photocatalytic applications.

ABSTRACTIn this paper, the biological applications of synthetic dysprosium(III) complex, with 4,5-diazafluoren-9-one (dafone) ligand, including DNA/BSA interaction, antibacterial and anticancer activity were studied in vitro. The bovine serum albumin (BSA) and fish DNA (FS-DNA) binding of the dysprosium complex were studied by multi-spectrophotometric as well as computational calculation. Its DNA and BSA binding ability were estimated by fluorescence, absorption, circular dichroism spectroscopy, and viscosity measurements (only for DNA). The Dy-complex binds to DNA and BSA presenting high binding constants. For both DNA/BSA binding, the negative signs of thermodynamic parameter confirmed that hydrogen bonds and van der Waals forces play a main role in the interaction process. The competitive experiments with ethidium bromide (EtBr) and rhodamine B exhibited that the Dy-complex interacts with DNA via groove binding. The BSA competitive experiments showed that Dy-complex interacts with site 3 of BSA, which was completely arranged by docking studies. This complex showed high antimicrobial and cytotoxicity. Besides, nanocarriers of Dy-complex were produced, and the anticancer activities of these compounds were measured. (This paper provides a manifestation of a new tradition by which Comments on Inorganic Chemistry starts publishing original research content that, nonetheless, preserves the Journal’s identity as a niche for a critical discussion of contemporary literature in inorganic chemistry) (For previous manifestations, see Comments Inorg. Chem. 2018, 38, 1–35; 2019, 39, 1–26; 2019, 39, 188–215; 2020, 40, 1–24; 2020, 40, 277–303; 2021, 1–46, doi: 10.1080/02603594.2021.1962310.)

ABSTRACTThe complexation of gadolinium(III) with citric acid in aqueous solutions was studied by pH-metric titration, proton magnetic relaxation, and mathematic simulation in the pH range 2.0–10 at [Gd3+]: [H4Cit] = 1:1, 1:2, 1:3 ([Gd3+] = 1.3, 2.6, 5.0, 10.0, and 20.0 mmol L−1). In the process of simulation, the equilibrium composition, a model obtained from previously known works and including mono- and bis-citrate complexes of gadolinium(III) was taken as a basis. In this work, it is shown that a satisfactory description of the experimental data set of two independent physico-chemical methods is achieved only with the additional inclusion of citrate complexes of gadolinium(III) with higher degree of protonation and some new polynuclear complexes. The complex [GdH4Cit]3+ with the molecular form of the citrate ligand, and the polynuclear complexes [Gd2(HCit)2]°, [Gd2Cit2]2-, [Gd6(OH)2Cit6]8-, [Gd6(OH)3Cit6]9- were first detected at the molar ratio of 1:1. At two- and three-fold excess of citric acid, mononuclear bis- and tris-citrate complexes with different degrees of protonation were found, and binuclear tetrakis- and hexakis-citrate complexes [Gd2(HCit)Cit3]9-and [Gd2(HCit)4Cit2]14- at the pH > 7.5. On the example of this manuscript, the importance of applying the NMR relaxation method for identifying polynuclear complexation in systems containing paramagnetic ions is shown.

ABSTRACTXPS analyses of open shell ionic compounds, especially oxides of the first row transition metals, for information such as oxidation state tend to focus on characteristics of the metal 2p XPS features alone. These analyses could be made considerably more robust with simultaneous characterization of the XPS of the metal 3p features as well as the 2p features. In these comments, we provide a perspective on the conceptual and theoretical framework needed to extract chemical information from the complex multiplet structure of the 3p XPS of Fe oxides as representative of 3d transition metal oxides. We also present information about a novel kind of many-body effects that may contribute to a further redistribution of the Fe 3p XPS intensity. The concern here is not to develop a complicated mathematical formalism but to explain the complexity in terms of fundamental quantum mechanical concepts. This is done on the basis of ab initio Dirac Hartree–Fock wavefunctions where we examine the physical nature of the 3p XPS features of the representative ferrous and ferric oxides of FeO and Fe2O3, respectively. The key objectives of this paper are as follows: (1) to demonstrate the importance of the angular momentum coupling of open shell electrons, which is done more easily with RS multiplets; (2) to show that a single configuration description of the final state multiplets is woefully inadequate; (3) to identify a novel atomic many-body effect that can lead to a rich satellite structure. The considerations discussed here should have implications for making useful interpretations of the XPS of lower BE levels of other ionic, high spin materials. This paper provides a manifestation of a new tradition by which Comments on Inorganic Chemistry starts publishing original research content that, nonetheless, preserves the Journal’s identity as a niche for critical discussion of contemporary literature in inorganic chemistry; for previous manifestations, see Comments Inorg. Chem. 2020, 40, 277–303 and references cited in the abstract thereof.

ABSTRACT This paper provides the fifth manifestation of a new tradition by which the editors of Comments on Inorganic Chemistry wish to lead by example, whereby we start publishing original research content that, nonetheless, preserves the Journal’s identity as a niche for critical discussion of contemporary literature in inorganic chemistry (For the previous manifestations, see: Comments Inorg. Chem. 2018, 38, 1–35; 2019, 39, 1–26; 2019, 39, 188–215; 2020, 40, 1–24.) Herein, synthetic details, solid-state structures, and photophysical properties of a group of silver(I) and copper(I) complexes are described. Two silver-based coordination polymers have been obtained: {[3,5-(CF3)2Pz]2(bpp)Ag2}∞ (1) and {[3,5-(CF3)2Pz][5-(C6F5)Ttz](bpp)Ag}∞ (2) – constructed from bent 1,3-bis(4-pyridyl)propane (bpp), 3,5-bis(trifluoromethyl)pyrazole ([3,5-(CF3)2Pz]H) and 5-pentafluorophenyl-tetrazole ([5-(C6F5)Ttz]H) in order to inspect the influence of mixed ligands on the resulting silver-based coordination complexes. The structure of 1 shows a distorted trigonal planar geometry with both the bpp and [3,5-(CF3)2Pz] ligands binding to the silver atom. The silver in 2 shows an uncommon interaction with the three different ligands. Also, two different geometries including distorted tetrahedral and distorted trigonal were presented for two different silver atoms. An interesting result was obtained for the Cu(I) coordination polymer {[Cu(bpp)2][BF4]}∞ (3) which was successfully synthesized in a solventless reaction but not a solvent-mediated reaction, hence manifesting a “green” chemistry route. The structure of 3 shows an ideal tetrahedral geometry similar to that for the silver analogue, {[Ag(bpp)2][BF4]}∞ (3a), published previously, whereas herein we obtained the same product with the same crystal structure via a more facile conventional synthetic route. All four complexes show bpp ligand-centered green emissions at ambient and cryogenic temperatures. Finally, a commentary is added to contrast the solventless vs solvent-mediated reactions in both this investigation and a precedent thereof by the same corresponding author’s group (Inorg. Chem. 2018, 57, 9962–9976), whereby reactions proceeded successfully only via the solventless route through mechanical grinding herein and spontaneous sublimation by vapor diffusion from the solid-state of one reactant to another yet nonvolatile reactant in the literature precedent, respectively.

ABSTRACTWe point-out an exceptional tailorability of iron(III) trimesate metal-organic framework to bio-friendly conditions. This is particularly attractive in sight of one-pot immobilization of biomolecules for biomedical applications. Synthesis is carried out via mechanochemical approach under green, biocompatible conditions without additional solvents, in just 1 hour, at room temperature. Solvents are proven to be unnecessary to build the framework, in contrast to solution-based methods. Microstructure and thermal stability of the material are not affected by pH. Conversely, textural properties can be tuned by simply varying the amount of base.

Trinuclear coinage metal metallacycles are obtained when two-coordinate metals are bonded to C, N or N, N anionic ligands of the proper symmetry to form cycles where metals alternate with bridging ligands. Cyclotrimers often exhibit semiplanar structures and mostly columnar or finite stacking in the solid state by means of metallophilic interactions. They show some peculiar properties with an impact on many different fields such as supramolecular architectures, luminescence, molecular recognition, host-guest chemistry, and acid-base chemistry. The comprehensive evaluation of the data shows that, depending on the nature of the central metal and bridging ligand, there is a fine balance of the energy involved in the inter-trimer bond cleavages and the energy gained from the formation of new intermolecular electrostatic interactions, proceeding occasionally to the chemical extreme of redox processes. In this review, a number of important developments are highlighted and systematically analyzed along with structural and computational data and chemical properties to rationalize and build a unifying leitmotif for this chemistry; the focus is made on the authors’ contributions in these areas.

ABSTRACTAs a product of photosynthesis, the storable chemical energy in the form of carbohydrates inspires the people engaged in renewable energy research to mimic the natural process. This may be the reduction of the proton or carbon dioxide to produced fuels e.g., hydrogen or CH4 and CH3OH or other chemical feed stocks e.g., HCOOH, CO32-. (COOH)2. This replication of the natural process is known as Artificial Photosynthesis. In either case water oxidation is mandatory. Herein, we discuss brief mechanism of photosynthesis, emphasizing the role of Water Oxidation Catalyst (WOC). Literature on Manganese based WOC is presented with their characteristic features.

ABSTRACTThe development of appropriate luminophores for detecting nitroaromatic explosives is a crucial issue for our safety and security. In the past decade, astounding efforts have been made towards the development of phosphorescent iridium probes based on diverse sensing mechanisms for explosive detection. Phosphorescent iridium materials possess unique properties such as long-lived phosphorescence, high quantum efficiency, and modular syntheses that render them as suitable alternatives to organic dyes. According to the literature, many of the iridium molecular probes used to detect nitroaromatics are ”turn-off” luminescence sensors. Thus, the review describes the current state-of-the-art, its accomplishments, unique challenges, and future directions.

ABSTRACTHydrogen (H2) is examined as a fuel and as one of the most extensively studied substitute energy resources for available sources that are being consumed rapidly. Thus, the growing interest in the development of competitive, low-cost hydrogen production leads us to devote particular efforts to establish efficient processes in an economical and environmentally benign way. In this view, both photochemical and electrochemical processes have been exclusively investigated as greener paths for hydrogen production. The present review article highlights the process established for hydrogen generation over the last few years. The overall thrust of the present theme is a discussion of the efforts that have been made so far for finding hydrogen as an alternative fuel from different feedstock through photochemical and electrochemical processes.

ABSTRACTThis paper provides a manifestation of a new tradition by which Comments on Inorganic Chemistry starts publishing original research content that, nonetheless, preserves the Journal’s identity as a niche for a critical discussion of contemporary literature in inorganic chemistry; for previous manifestations, see Comments Inorg. Chem. 2020, 40, 277-303 and references cited in the abstract thereof as Yaseen W. K.; Sanders S. F.; Almotawa R. M.; Otten B. M.; Bhat S.; Alamo D. C.; Marpu S. B.; Golden T. D.; Omary M. A. “Are Metal Complexes” Organic, Inorganic, Organometallic, or Metal-Organic Materials? A case Study for the Use of Trinuclear Coinage Metal Complexes as “Metal-Organic Coatings” for Corrosion Suppression on Aluminum Substrates Comments Inorg. Chem. 2019, 39, 1-26 and also, Mohapatra R. K.; Das P. K.; Pradhan M. K.; El-Ajaily M. M.; Das D.; Salem H. F.; Mahanta U.; Badhei G.; Parhi P. K.; Maihub A. A.; Kudrat -E-Zahan Md. “Recent Advances in Urea- and Thiourea-Based Metal Complexes: Biological, Sensor, Optical, and Corrosion Inhibition Studies” Comments Inorg. Chem. 2019, 39, 127-147).In this work, the Schiff base 1-(6-(1-((4-(4-aminophenoxy)phenyl)imino)ethyl)-pyridin-2-yl)ethan-1-one (L) and eight transition metal complexes were synthesized. The reaction of 4,4-oxy-dianiline with 2,6-diacetylpyridine in 1:1 molar ratio affords to the ligand which was employed in the synthesis of the corresponding metal complexes by reacting with the Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) chlorides in 1:1 molar ratio. All the compounds were characterized by using different analytical methods. Structures of complexes were found to be octahedral as deduced from the spectroscopic and magnetic moment measurements. The ligand behaves as a neutral tridentate ligand where it coordinated to metal ions through N-azomethine, N-pyridine, and O-carbonyl group. Besides, experimental investigations for their antibacterial activity against different bacteria species were studied, molecular docking studies were reported with receptors 4ME7, 4K3V, 3T88 and 4WJ3. Density functional theory (DFT) calculations for ligand were reported. Finally, the evaluation of corrosion inhibition efficiency was measured by using different techniques such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and electrochemical frequency modulation (EFM). Scanning electron microscope (SEM) and energy dispersive X-Ray analysis (EDX) were measured to affirm the presence of barrier film on the carbon steel surface by inspecting the surface morphologies and elemental composition of corrosion products.