Inorganic Moieties Research Articles

Chirality-Mediated 1D-to-2D Phase Transition in Hybrid Lead Halide Perovskites.

Dimensionality engineering plays a pivotal role in optimizing the performance, ensuring long-term stability, and expanding the versatile applications of lead halide perovskites (LHPs). Currently, the manipulation of LHP dimensions primarily occurs during the synthesis stage, a procedure hampered by constraints, including synthetic complexity and irreversibility. This investigation successfully achieved a transition from one-dimensional (1D) to two-dimensional (2D) structures in chiral LHPs by applying hydrostatic pressure. Remarkably, this pressure-induced transition in dimensionality is absent in the racemic analogue due to the staggered arrangement of inorganic chains and the elevated steric hindrance posed by the organic cations. Notably, the hydrogen bonding between organic cations and the inorganic framework adopts a symmetrical arrangement in the racemic system but a helical configuration along the 1D chain direction in the chiral counterparts. This distinct helical arrangement induces a consequential distortion in the inorganic moiety, resulting in the emergence of a spin-polarized Rashba-Dresselhaus texture that explains the chirality's electronic spin origin. Furthermore, both experimental and density functional theory calculation results demonstrate that the 1D-to-2D phase transition in chiral halide perovskites can induce significant modifications in the electronic structures and associated optical emissions. In summary, the findings unveil novel avenues for manipulating optoelectronic properties in chiral perovskites through dimensionality engineering.

Chirality and Solvent Coassist the Structural Evolution of Hybrid Manganese Chlorides with Second-Harmonic-Generation Response.

Chiral hybrid metal halides have shown great potential in optoelectronics, including for spin splitting, circularly polarized luminescence, and nonlinear-optical properties. However, despite their inherent inversion symmetry breaking, studies on second harmonic generation (SHG) of chiral hybrid manganese(II) halides remain relatively rare. Here, we report a series of structurally diverse hybrid manganese(II) chlorides: (Rac-MBA)2[MnCl4(H2O)2] (1), (S-MBA)2[MnCl4(H2O)2] (2), (S-MBA)2[Mn2Cl6(H2O)4] (3), and (S-MBA)[MnCl3(MeOH)] (4), where MBA = α-methylbenzylammonium, providing tunability of the coordination environment and structural dimensionality via fine control of the MBA cation chiral state and crystal preparation process, thereby enabling modulation of the SHG effects. Specifically, as the amount of methanol increases during the crystal preparation process, the structures of the chiral compounds vary from a 0D structure consisting of isolated octahedra to a 0D structure composed of octahedra dimers and to 1D chains of edge-sharing Mn-centered octahedra. In contrast, the structure of the racemic compound remains unchanged, independent of the crystal preparation pathway. The structural details, including the coordination environment, H-bonding, dimensionality, and lattice distortion, are described. The SHG response of the racemic compound derives only from the inorganic lattice, while the responses of the chiral compounds are attributed to the synergetic effect of the chiral cations and inorganic moieties.

Photoluminescence Enhancement of 0D Organic-Inorganic Metal Halides via Aggregation-Induced Emission and Halide Substitution.

0D organic-inorganic metal halides (OIMHs) provide unprecedented versatility in structures and photoluminescence properties. Here, a series of bluish-white emissive 0D OIMHs, (TPE-TPP)2Sb2BrxCl8-x (x = 1.16 to 8), are prepared by assembling the 1-triphenylphosphonium-4-(1,2,2-triphenylethenyl)benzene cation (TPE-TPP)+ with antimony halides anions. Based on experimental characterizations and theoretical calculations, the emission of the 0D OIMHs are attributed to the fluorescence of the organic cations with aggregation-induced emission (AIE) properties. The 0D structure minimized the molecular motion and intermolecular interactions between (TPE-TPP)+ cations, effectively suppressing the non-radiative recombination processes. Consequently, the photoluminescence quantum efficiency (PLQE) of (TPE-TPP)2Sb2Br1.16Cl6.84 is significantly enhanced to 55.4% as compared to the organic salt (TPE-TPP)Br (20.5%). The PLQE of (TPE-TPP)2Sb2BrxCl8-x can also be readily manipulated by halide substitution, due to the competitive processes between non-radiative recombination on the inorganic moiety and the energy transfer from inorganic to organic. In addition, electrically driven light-emitting diodes (LEDs) are fabricated based on (TPE-TPP)2Sb2Br1.16Cl6.84 emitter, which exhibited bluish-white emission with a maximum external quantum efficiency (EQE) of 1.1% and luminance of 335cdm-2. This is the first report of electrically driven LED based on 0D OIMH with bluish-white emission.

Single crystal investigations, hirshfeld surface analysis, DFT studies, Molecular docking and Physico-Chemical characterization of a Cu(II) dimethylpiperazinium salt

A novel centrosymmetric hybrid organic-inorganic material (1,4-dimethylpiperazine tetrachlorocuprate (II)) has been prepared and analyzed using single crystal X-ray diffraction, spectroscopic studies, photoluminescence properties, DFT studies and Hirshfeld surface analyses. The single crystal X-ray analysis indicates that the compound crystallizes in the P21/c monoclinic space group. The N–H···Cl hydrogen bonds are alternately connected by organic cations [C6H16N2]2+ and inorganic moieties [CuCl4]2-. The Hirshfeld surfaces investigated the nature and quantity of different interactions and their role in crystal packing. Infrared and Hirshfeld measurements were performed to confirm the results obtained by X-ray diffraction. In addition, optical measurements were used to investigate the IR and photoluminescence properties. The di-electrical investigations show interesting electrical behavior of the compound. In addition, an insilico investigation using molecular docking of the compound against SARS-CoV-2 variation (B.1.1.529) was also conducted to better understand the non-covalent interaction of cuprate(II) complexes with active amino acids in the SARS-CoV-2 spike proteins. These studies were supported by drug-likeness and absorption, distribution, metabolism, and excretion (ADME) analyses.

The key role of methylenediammonium and tetrahydrotriazinium in the phase stability of FAPbI3

Formamidinium lead triiodide (FAPbI3) is the prime candidate for single-junction perovskite solar cells, despite the metastability of the phase. To improve its ambient-phase stability and produce world-record photoelectric conversion efficiencies, methylenediammonium (MDA) has been used as an additive in FAPbI3. However, the exact function and role of MDA are still uncertain. The MDA doping may exist in the perovskite lattice in either the original structure or the THTZ-H (tetrahydrotriazinium) structure. In this research, the effects of the MDA and THTZ-H doping FAPbI3 perovskite on its stability are explored by first-principles calculations. Both MDA and THTZ-H doping can improve the stability of FAPbI3 perovskite from a structural perspective due to lattice strain and stronger H–I bonds. However, the doping mechanisms differ significantly in terms of electronic properties. The MDA doping acts by the traditional passivation mechanism. It can eliminate the iodine interstitial defect states that trap charge carriers and inhibit iodine interstitial defect migration. The THTZ-H cation can directly contribute to the band edge construction in the FAPbI3 bulk. Electron delocalization in the π-conjugated ring structure lowered the frontier orbital separation of the THTZ-H organic molecule and enabled orbital overlap with the inorganic moiety. The in-depth understanding of the mechanism of improving stability in this study would facilitate the application of FAPbI3 perovskite optoelectronic devices.

Synthesis and electrochemical studies of 1,1’-binaphthyl-2,2’-diol for aqueous rechargeable lithium-ion battery applications

The constant increase in the utilization of lithium-ion batteries (LIBs) in various field applications, including electrical vehicles and electronic devices, has led researchers to focus on their multiple path developments to obtain new electrode materials. The practical development of these electrode materials, based on organic and inorganic moieties, is challenging for various groups of LIB scientists. The concept of organic electrode materials is highly competitive with inorganic electrode materials because of the accessibility of more active sites with structural diversity, high energy and power density, environmental friendliness potential sustainability, and low cost. Herein, 1,1’-binaphthyl-2,2’-diol (BINOL) is investigated as an organic electrode material that contains two hydroxyl groups that act as active centers. The oxidative coupling process is employed to synthesize BINOL and so obtained product was characterized by using FT-IR, 1H-NMR and MASS techniques. The electrochemical investigations were carried out using sat. Li2SO4 electrolytic medium at three-electrode cell system. The Cyclic voltammetry (CV) has provided information on the anodic behavior of the material and its stability studied at different scan rates. The battery performance of the cell BINOL | Sat. Li2SO4 | LiMn2O4 by galvanostatic charge-discharge potential limit (GCPL) shows 197/171mAhg−1 specific capacity and 90% columbic efficiency. The electrochemical kinetic obtained by potentiostatic electrochemical impedance spectroscopy (PEIS) shows a semi-infinite diffusion process.

Silk Industry Waste Protein-Derived Sericin Hybrid Nanoflowers for Antibiotics Remediation via Circular Economy.

Hybrid protein-copper nanoflowers have emerged as promising materials with diverse applications in biocatalysis, biosensing, and bioremediation. Sericin, a waste biopolymer from the textile industry, has shown potential for fabricating such nanoflowers. However, the influence of the molecular weight of sericin on nanoflower morphology and peroxidase-like activity remains unexplored. This work focused on the self-assembly of nanoflowers using high- and low-molecular-weight (HMW and LMW) silk sericin combined with copper(II) as an inorganic moiety. The peroxidase-like activity of the resulting nanoflowers was evaluated using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and hydrogen peroxide (H2O2). The findings revealed that high-molecular-weight sericin hybrid nanoflowers (HMW-ShNFs) exhibited significantly higher peroxidase-like activity than low-molecular-weight sericin hybrid nanoflowers (LMW-ShNFs). Furthermore, HMW-ShNFs demonstrated superior reusability and storage stability, thereby enhancing their potential for practical use. This study also explored the application of HMW-ShNF for ciprofloxacin degradation to address the environmental and health hazards posed by this antibiotic in water. The results indicated that HMW-ShNFs facilitated the degradation of ciprofloxacin, achieving a maximum degradation of 33.2 ± 1% at pH 8 and 35 °C after 72 h. Overall, the enhanced peroxidase-like activity and successful application in ciprofloxacin degradation underscore the potential of HMW-ShNFs for a sustainable and ecofriendly remediation process. These findings open avenues for the further exploration and utilization of hybrid nanoflowers in various environmental applications.

Microbial exopolysaccharide composites with inorganic materials and their biomedical applications: A review

Microbial exopolysaccharides (EPS) are high molecular weight carbohydrate-based materials produced and secreted in response to external environmental stress to protect microbial cells. These molecules also contain non-carbohydrate moieties including acetate, pyruvate, phosphate, and succinate along with sugar molecules. EPS has been incorporated into industrial operations as a gelling, emulsifying, and stabilizing agent to increase viscosity. Besides, these molecules have also shown high biocompatibility, immunomodulatory, antitumor, anti-microbial, and anti-viral activity which suggest their possible applications in healthcare. However, these molecules are facing some commercial shortcomings due to low stability, bioactivity, and poor mechanical and tensile strength in comparison to the required standard. Hence use of composites of EPS with other polymers and moieties has been suggested for higher performance. Especially in the context of inorganic moieties like silver, gold nanomaterials, clay, salts, and minerals will add bioactivity and functional sites for the attachment of drug molecules and other compounds. The current review summarizes the higher physical and chemical characteristics of EPS composites with inorganic materials and their immense potential in the biomedical sector.

The Copper Reduction Potential Determines the Reductive Cytotoxicity: Relevance to the Design of Metal-Organic Antitumor Drugs.

Copper-organic compounds have gained momentum as potent antitumor drug candidates largely due to their ability to generate an oxidative burst upon the transition of Cu2+ to Cu1+ triggered by the exogenous-reducing agents. We have reported the differential potencies of a series of Cu(II)-organic complexes that produce reactive oxygen species (ROS) and cell death after incubation with N-acetylcysteine (NAC). To get insight into the structural prerequisites for optimization of the organic ligands, we herein investigated the electrochemical properties and the cytotoxicity of Cu(II) complexes with pyridylmethylenethiohydantoins, pyridylbenzothiazole, pyridylbenzimidazole, thiosemicarbazones and porphyrins. We demonstrate that the ability of the complexes to kill cells in combination with NAC is determined by the potential of the Cu+2 → Cu+1 redox transition rather than by the spatial structure of the organic ligand. For cell sensitization to the copper-organic complex, the electrochemical potential of the metal reduction should be lower than the oxidation potential of the reducing agent. Generally, the structural optimization of copper-organic complexes for combinations with the reducing agents should include uncharged organic ligands that carry hard electronegative inorganic moieties.

Synthesis, crystal structure and luminescence of [(CH3)3S]2ZrCl6

The current work reports on the synthesis, crystal structure and optoelectronic properties of (Me3S)2ZrCl6, prepared by reacting the solid precursors (Me3S)Cl and ZrCl4 in pyrex tubes at 150 °C under vacuum. According to X-ray powder diffraction and Rietveld analysis, (Me3S)2ZrCl6 crystallizes in the cubic space group Pa-3 (No. 205) with a = 12.4664(1) Å. The crystal structure consists of isolated trigonal pyramidal trimethylsulfonium cations and octahedral [ZrCl6]2- anions with weak hydrogen bonds among them and no signs of structural disorder. This 0D-material is stable in air and dissolves in water and dimethylformamide. Raman spectroscopy shows characteristic vibrational modes for the organic and inorganic moieties over the frequency range of 5–3200 cm−1. UV-Vis spectroscopy reveals a large band gap of 5.1 eV and a broadband luminescence with emission maximum at 465 nm in the solid state. The luminescent properties of (Me3S)2ZrCl6 are discussed and compared with those of similar inorganic or metal-organic compounds.

Chiral zero-dimensional hybrid organic–inorganic metal halides based on nipecotic acid and tetrabromocuprate

Chiral 0D hybrid organic–inorganic metal halides with narrow bandgap and high thermal stability have been constructed from chiral amino acids and copper salt.

Bridging Component Strategy in Phosphomolybdate-Based Sensors for Electrochemical Determination of Trace Cr(VI).

Rapid and sensitive electrochemical determination of trace carcinogenic Cr(VI) pollutants remains an urgent and important task, which requires the development of active sensing materials. Herein, four cases of reduced phosphomolybdates with formulas of the (H2bib)3[Zn(H2PO4)]2{Mn[P4Mo6O31H7]2}·6H2O (1), (H2bib)2[Na(H2O)]2[Mn(H2O)]2{Mn[P4Mo6O31H6]2}·5H2O (2), (H2bib)3[Mo2(μ2-O)2(H2O)4]2{Ni[P4Mo6O31H2]2}·4H2O (3), and (H2bib)2{Ni[P4Mo6O31H9]2}·9H2O (4) (bib = 4,4'-bis(1-imidazolyl)-biphenyl) were hydrothermally synthesized under the guidance of a bridging component strategy, which function as effective electrochemical sensors to detect trace Cr(VI). The difference of hybrids 1-4 is in the inorganic moiety, in which the reduced phosphomolybdates {M[P4MoV6O31]2} (M{P4Mo6}2) exhibited different arrangements bridged by different cationic components ({Zn(H2PO4)} subunit for 1, [Mn2(H2O)2]4+ dimer for 2, and [MoV2(μ2-O)2(H2O)4]6+ for 3). As a result, hybrids 1 and 3 display noticeable Cr(VI) detection activity with low detection limits of 14.3 nM (1.48 ppb) for 1 and 6.61 nM (0.69 ppb) for 3 and high sensitivities of 97.3 and 95.3 μA·mM-1, respectively, which are much beyond the World Health Organization's detection threshold (0.05 ppm) and superior to those of the contrast samples (inorganic Mn{P4Mo6}2 salt and hybrid 4), even the most reported noble-metal catalysts. This work supplies a prospective pathway to build effective electrochemical sensors based on phosphomolybdates for environmental pollutant treatment.

Surface Functionalized Mesoporous Silica Nanoparticles for Enhanced Removal of Heavy Metals: A Review

Human health and environmental sustainability are strongly influenced by the contamination of water resources with hazardous heavy metal ions due to the accumulation in human body via food chains. Thereby, researchers’ attention has been paid on effective methods for heavy metal ion scavenging to prevent them releasing to environment. Notably, Mesoporous Silica Nanoparticles (MSNPs) with high surface area, massive surface area to volume ratio, large pore volume and uniform pore distribution play a crucial role in addressing this challenge. Additionally, researchers focus on novel surface functionalization methods of MSNPs with suitable organic and inorganic moieties to amplify the adsorption efficiency of heavy metals. MSNPs possess easily functionalizable surface which facilitates the modifications and enhanced removal of heavy metals. The review article summarizes the different moieties used for functionalization of MSNPs such as amino, thio, carboxyl, phenyl, cyano groups, different types of polymers, inorganic functional groups. Further, a comparison has been made between functional and unmodified MSNPs to elaborate how these modifications have enhanced the removal performance of heavy metals in water. Further, this review provides an overview on different synthesis routes and structure directing agent used in synthesis of MSNPs. Moreover, pH effect on adsorption andreusability of modified NPs, while illustrating the mechanism of adsorption on to modified MSNPs surface has also been elaborated. Maximum adsorption capacity of each functional moiety has been taken into consideration with the aim of supporting future advancements.
 Keywords: Adsorption, Mesoporous silica nanoparticles, Heavy metals, Functionalization, Maximum adsorption capacity

Supramolecular-Interactions-Modulated Photoluminescence in Indium Bromide-Based Isomers.

Here, two isomeric ionic zero-dimensional indium bromide crystals of α (1)/β (2)-[OPy][InBr4(Phen)] (OPy = N-octylpyridinium; Phen = 1,10-phenanthroline) have been isolated simply by changing the cooling conditions in solvothermal syntheses. Structural comparisons indicate their different supramolecular interactions, which can be confirmed by Hirshfeld surface analyses. The crystal 2 has additional hydrogen bonds and π-π interactions; as a result, the more compact stacking of 2 could result in a 10-fold higher photoluminescence (PL) quantum yield (PLQY) than that of 1. Density functional theory calculations confirm the electron transition from the inorganic moiety to the organic ligand, which provides a further understanding of the optical process. This work provides a new idea for designing PL indium-based halides by understanding the structure-PL relationship.

Amino-Alcohol Organic-Inorganic Hybrid Sol-Gel Materials Based on an Epoxy Bicyclic Silane: Synthesis and Characterization.

Organic-inorganic hybrids (OIHs) are a type of material that can be obtained using the sol-gel process and has the advantages of organic and inorganic moieties in a single material. Polyetheramines have been widely used in the preparation of this type of material, particularly in combination with epoxy-based alkoxysilanes. Nevertheless, epoxyciclohexylethyltrimethoxysilane (ECHETMS) is a promising alkoxysilane with an epoxy terminal group that is quite unexplored. In this work, four novel OIH materials were synthesized using the sol-gel method. The OIHs were based on Jeffamines® of different molecular weights (D-230, D-400, ED-600, and ED-900), together with ECHETMS. The materials were characterized using multinuclear solid state NMR, FTIR, BET, UV/Vis spectroscopy, EIS, and TGA. The influence of the Jeffamine molecular weight and the suitability of these materials to act as a supporting matrix for heteroaromatic probes were assessed and discussed. The materials show interesting properties in order to be applied in a wide range of sensing applications.

α- and β-(C4H5N2O)(IO3)·HIO3: Two SHG Materials Based on Organic-Inorganic Hybrid Iodates.

Organic-inorganic hybrid nonlinear optical (NLO) materials are highly anticipated because of the integration of both merits of the organic and inorganic moieties. Herein, the 2-pyrimidinone cation (C4H5N2O)+ has been incorporated into the iodate system to form two polymorphic organic-inorganic hybrid iodates, namely, α- and β-(C4H5N2O)(IO3)·HIO3. They crystallize in different polar space groups (Ia and Pca21), and their structures feature one-dimensional (1D) chain structures composed of (C4H5N2O)+ cations, IO3- anions, and HIO3 molecules interconnected via hydrogen bonds. α- and β-(C4H5N2O) (IO3)·HIO3 exhibit strong and moderate second-harmonic-generation (SHG) responses of 6.4 and 0.9 × KH2PO4 (KDP), respectively, the same band gaps of 3.65 eV, and high powder laser-induced damage threshold (LIDT) values [51 and 57 × AgGaS2 (AGS)]. The results of theoretical calculations revealed that the large SHG effect of α-(C4H5N2O)(IO3)·HIO3 originated from the IO3 and HIO3 groups. This work indicates that (C4H5N2O)+ is a potential group for designing new NLO materials with brilliant optical performances.

Sol-gel synthesis, physico-chemical characterization and investigations on ion exchange performance of atypical conducting polymer integrated composite cation exchangers

ABSTRACT Herein, an effective sol-gel strategy was utilized for the synthesis of atypical Polypyrrole/EDTA-Zirconium(IV) phosphate (PYZP) and Polypyrrole/EDTA-Zirconium(IV) iodate (PYZI) composite cation exchangers. The structural aspects, surface morphology, elemental composition and thermal constancy of the aforementioned composite cation exchangers were scrutinized through UV-Visible, FT-IR, XRD, SEM with EDAX, TEM and TGA studies. As-prepared conducting polymeric composite materials divulged not only excellent ion exchange capacity but also better thermal stability, electrical conductivity and notable selectivity toward Pb(II) ions as compared to their individual inorganic moieties. The improvement in ion exchange capacities (IEC) for distinct alkali metal ions of PYZP composite cation exchanger were Li+, 2.89; Na+, 3.15; K+, 3.34 meq/g and PYZI composite cation exchanger were Li+, 2.60; Na+, 2.86; K+, 3.21 meq/g, separately. It was concluded that PYZP composite acts as an excellent cation exchanger compared to PYZI composite due to the presence of ionogenic phosphate anions. The partition competency of the composite materials toward distinct metal ions in diverse solvent systems exposed the separation potentials of metal ions of systematic prominence from a specified binary combinations encompassing Cd(II) – Pb(II), Hg(II) – Pb(II), Cu(II) – Pb(II), Zn(II) – Pb(II), Ni(II) – Pb(II) and Fe(III) – Pb(II) metal ions. Subsequently, the conducting competency was examined through AC-Impedance spectroscopy.

Isoreticular Contraction of Metal-Organic Frameworks Induced by Cleavage of Covalent Bonds.

Isoreticular chemistry, in which the organic or inorganic moieties of reticular materials can be replaced without destroying their underlying nets, is a key concept for synthesizing new porous molecular materials and for tuning or functionalization of their pores. Here, we report that the rational cleavage of covalent bonds in a metal-organic framework (MOF) can trigger their isoreticular contraction, without the need for any additional organic linkers. We began by synthesizing two novel MOFs based on the MIL-142 family, (In)BCN-20B and (Sc)BCN-20C, which include cleavable as well as noncleavable organic linkers. Next, we selectively and quantitatively broke their cleavable linkers, demonstrating that various dynamic chemical and structural processes occur within these structures to drive the formation of isoreticular contracted MOFs. Thus, the contraction involves breaking of a covalent bond, subsequent breaking of a coordination bond, and finally, formation of a new coordination bond supported by structural behavior. Remarkably, given that the single-crystal character of the parent MOF is retained throughout the entire transformation, we were able to monitor the contraction by single-crystal X-ray diffraction.

Surfactant-Assisted Synthesis of Mesoporous Metal Phosphonates to Control Surface Properties Including an Opportunity to Organize a Bulky Biphenyl Linker.

A wide variety of properties by the presence of functional organic groups have so far been investigated by using periodic mesoporous organosilica (PMO)-type materials but not yet discussed with surface properties that are controlled through the success in synthesizing analogous non-silica-based hybrid mesoporous materials and subsequent evaluation and/or comparison of their properties. Here, we demonstrated the advance in synthesizing biphenyl group (-Ph-Ph-, also expressed as -2Ph)-containing mesoporous metal phosphonates with a rational understanding of surface properties. Ordered mesoporous films of aluminum and titanium ones (AOP-2Ph and TiOP-2Ph) were fabricated by spin-coating and their powders were recovered by spray-drying with the confined assembly of spherical mesopores. As in the case of PMO-type materials, the possibility to organize a -Ph-Ph- linker at the molecular scale was found in the powder samples of AOP-2Ph and TiOP-2Ph because thick frameworks would give an opportunity to organize the bulky -Ph-Ph- linker as the small-sized domains even around spherical mesopores. Surface properties of AOP-2Ph and TiOP-2Ph were evaluated by using the data of water (H2O) adsorption isotherms and compared with those containing different organic groups. The unique hydrophilicity starting from the hydration of AlO4 units was drastically reduced by the presence of -Ph-Ph- groups with a disappearance of the capillary condensation by the presence of mesopores. In addition, a partial replacement of TiO6 units with AlO4 and/or its hydrated AlO6 species was proposed for decreasing the strong hydrophobicity of TiOP-2Ph. The contact angle over the spin-coated films was also measured by using a droplet of H2O, indicating that the surface of the films, especially TiOP-2Ph, was extremely hydrophilic. Although surface properties at the molecular scale can be evaluated by using molecular H2O vapor during the measurement of H2O adsorption isotherms, the interaction of the H2O cluster (droplet) with the bulk surface seems to be predominated by inorganic moieties.

Methylammonium Tetrel Halide Perovskite Ion Pairs and Their Dimers: The Interplay between the Hydrogen-, Pnictogen- and Tetrel-Bonding Interactions.

The structural stability of the extensively studied organic-inorganic hybrid methylammonium tetrel halide perovskite semiconductors, MATtX3 (MA = CH3NH3+; Tt = Ge, Sn, Pb; X = Cl, Br, I), arises as a result of non-covalent interactions between an organic cation (CH3NH3+) and an inorganic anion (TtX3-). However, the basic understanding of the underlying chemical bonding interactions in these systems that link the ionic moieties together in complex configurations is still limited. In this study, ion pair models constituting the organic and inorganic ions were regarded as the repeating units of periodic crystal systems and density functional theory simulations were performed to elucidate the nature of the non-covalent interactions between them. It is demonstrated that not only the charge-assisted N-H···X and C-H···X hydrogen bonds but also the C-N···X pnictogen bonds interact to stabilize the ion pairs and to define their geometries in the gas phase. Similar interactions are also responsible for the formation of crystalline MATtX3 in the low-temperature phase, some of which have been delineated in previous studies. In contrast, the Tt···X tetrel bonding interactions, which are hidden as coordinate bonds in the crystals, play a vital role in holding the inorganic anionic moieties (TtX3-) together. We have demonstrated that each Tt in each [CH3NH3+•TtX3-] ion pair has the capacity to donate three tetrel (σ-hole) bonds to the halides of three nearest neighbor TtX3- units, thus causing the emergence of an infinite array of 3D TtX64- octahedra in the crystalline phase. The TtX44- octahedra are corner-shared to form cage-like inorganic frameworks that host the organic cation, leading to the formation of functional tetrel halide perovskite materials that have outstanding optoelectronic properties in the solid state. We harnessed the results using the quantum theory of atoms in molecules, natural bond orbital, molecular electrostatic surface potential and independent gradient models to validate these conclusions.