Structural Chemistry

Article	Citations
Synthesis, spectral characteristics and molecular structure of N-(1-(5-amino-1H-1,2,4-triazol-1-yl)-2,2,2-trichloroethyl)carboxamides	42
Fragment-based inhibitor design for SARS-CoV2 main protease	42
Synthesis, characterizations, and computational studies of new tetrasubstituted imidazole containing a benzothiazole moiety	37
Salts containing different amino acids: l-argininium ( +) sarcosine halogenides	37
Size evolution and property study on PdAgn (n = 1–17) clusters from density functional theory	36
Impact of hetero-atom doping on electronic structure and reactivity of anionic Al13− cluster: a combined density functional theory and global optimization investigation	36
Synthesis, Spectral Properties, Crystal Structure and DFT Studies of 2-((1-Phenyl-1H-1,2,3-triazol-4-yl)methoxy)benzonitrile	34
Elucidation of the enantiomer migration order of atenolol by theoretical calculations	33
On substituent effect in 1,n–homodisubstituted polyenes	31
Crystal structure and Hirshfeld surface analysis of copper(II) β-aminovinyl ketone complexes	30
Discovery of slow neutrons 90 years ago – A tribute to Enrico Fermi	30
Adsorption attributes of methyl naphthalene and naphthalene on P-Germanane sheets–a DFT outlook	27
Adsorption behavior of anti-cancer procarbazine on the surface of on pristine, Al-, Si-, and C-doped B24N24 fullerenes based on the density functional theory	27
Structure, vibrational characterization and DFT calculations of 1-(diaminomethylene)thiouron-1-ium 2,3-pyridinedicarboxylate	27
A DFT-based study to understand the adsorption of alanine on carbon nanocups	25
DFT and NBO computational calculations support Schleyer’s hyperconjugative enhancement of aromaticity concept	24
New bis-azido iron(III) meso-arylporphyrin complex: spectroscopic characterization, solid state molecular structure, DFT, MEP, QTAIM calculations and Hirshfeld surface analyses	24
Chemical modification-induced enhancements in quantum dot photovoltaics: a theoretical and molecular descriptive analysis	23
Tautomeric behavior of 1,2,4-triazole derivatives: combined spectroscopic and theoretical study	23
Synthesis, single crystal X-ray structure determination, Hirshfeld surface analysis, crystal voids studies, and density functional theory calculations of N-carbamothioylbenzamide and 1,3,5-triazinane-	23
Exploring structural requirements of simple benzene derivatives for adsorption on carbon nanotubes: CoMFA, GRIND, and HQSAR	23
Energy contribution of heterocyclic sulfur and a disulfide bond in solid and gaseous phase	22
Effect of hydrophobic groups on adsorption of arginine-based amino acids to solid surfaces in water	21
1,10-Phenanthroline-5,6-dione-bridged FeCo complexes: a DFT investigation of the electronic lability	20
Influence of water on the conformations and interactions within two choline chloride-based deep eutectic solvents: a density functional theory investigation	20

Theoretical study of the formation of pyrazole and indazole carbamic acids	19
Different topology of mixed valence CoIICoIII complexes with SCN anions and hydrazone–pyridine-based ligands	18
Structural evolution and electronic properties of medium-sized CrSin−/0 (n = 19–25) clusters	18
Computational study on alkali and alkaline earth metal decorated B20 cluster for hydrogen storage application	17
The conceptual power of the Hellmann–Feynman theorem	17
Understanding the effect of first-row transition metals on the structure and properties of cyclopentadienyl-stabilized 5-metalla-1,3,2,4-dithiadiazoles	16
Investigation of structure–activity relationship: In silico studies of [1, 2, 4]triazolo[4, 3-a]pyridine ureas as P38 kinase inhibitors	16
In silico and biological exploration of greenly synthesized curcumin-incorporated isoniazid Schiff base and its ruthenium complexes	16
Design of hACE2-based small peptide inhibitors against spike protein of SARS-CoV-2: a computational approach	16
Molecular electronic structure and optical properties of benzo[imidazole]–benzo[thiazole] coupled derivatives using DFT and TD-DFT probe	15
A theoretical characterization of mechanisms of action of osmium(III)-based drug Os-KP418: hydrolysis and its binding with guanine	15
Targeting COVID-19 pandemic: in silico evaluation of 2-hydroxy-1, 2-diphenylethanone N(4)-methyl-N(4)-phenylthiosemicarbazone as a potential inhibitor of SARS-CoV-2	15
Structural, electronic, and energetic modifications in alkali metal-doped Ge₁₂C₁₂ nanocages for tuning nonlinear optical response, energetic offsets, and charge transfer dynamics: computational insigh	14
3D-QSAR, ADME-Tox, and molecular docking of semisynthetic triterpene derivatives as antibacterial and insecticide agents	14
Prediction of the lowest energy structure of Sn(BH4)2 and its electronic properties	14
Baruch S. Blumberg’s centennial—a Nobel laureate cutting through scientific disciplines	14
Effect of sulfur defects on the photoelectric and magnetic properties of metal-doped CrS2: first-principles study	14
Exploring extremal molecular characteristics: insights from nanosheets and polycyclic aromatic hydrocarbons	14
The structure and Hirshfeld surface analysis of the 4-amino 3-nitrobenzoic acid triclinic polymorph	14
Antiviral phytocompounds “ellagic acid” and “(+)-sesamin” of Bridelia retusa identified as potential inhibitors of SARS-CoV-2 3CL pro using extensive molecular docking, molecular dynamics simulation s	14
Structure of alkylammonium cations and its effect on the thermal properties of alkylammonium hydrogen sulfates	13
Study insights into the different cyclization mechanisms of ethyl cyanoacetate with salicylaldehyde and efficient synthesis of coumarin-3-carboxylate ester	13
Theoretical study of novel antipyrine derivatives as promising corrosion inhibitors for mild steel in an acidic environment	13
Revised structure of 2,13-dinitro-5,10,15,20-tetraphenylporphyrin. Inside high-resolution NMR	13
Theoretical study on the structures and properties of (HF)nH2O (n = 1–9) composite clusters	12
Tri-tert-butyl methane and its halogen analogues: a computational study of intramolecular interactions in a family of sterically crowded molecules	12
Electronic effects of the substituted dopants on stability and reactivity of difuranosilapyridine-4-ylidenes: DFT approach	12
Investigation of the influence of Z/E configuration on the antioxidant and antiradical activities of lapachol and its derivatives: DFT assessment	12
Forty years of quasicrystals: a bumpy road to triumph	12
Isomers and neutral precursors of the cyclopentenium ion, cyclo-C5H7+: structural diversity, vibrational spectra, and charge distribution	11
Theoretical investigation of structural parameters, reactivity behavior, and thermodynamic properties of Anderson polyoxometalate (POM)	11
In silico study to identify novel potential thiadiazole-based molecules as anti-Covid-19 candidates by hierarchical virtual screening and molecular dynamics simulations	11
Electrochemical performance of sodiated 1,4-benzoquinone conformers	11
Molecular insights into genistein-NSAID hybrids—synthesis, characterisation and DFT study	11
Theoretical study on the conformation and aromaticity of [13] to [33] double-stranded cyclophanes encompassing three benzene subunits	11
Applications of chem-bioinformatic, chemometric and machine learning approaches for COVID-19 related research	11
Repurposing FDA approved drugs as possible anti-SARS-CoV-2 medications using ligand-based computational approaches: sum of ranking difference-based model selection	11
Identification of SARS-CoV-2 inhibitors through phylogenetics and drug repurposing	11
On the quest of small molecules that can mimic Psalmotoxin-1, the most powerful peptidic modulator of the acid sensing channel ASIC1a	11
Phase change enthalpies of some monosubstituted derivatives of adamantane: an experimental and theoretical study	10
Unveiling the nature of interactions in the supramolecular complex of Cucurbit [7-8] uril with ascorbic acid, dopamine and uric acid for biosensing applications: a computational study	10
Molecular dynamic simulation suggests stronger interaction of Omicron-spike with ACE2 than wild but weaker than Delta SARS-CoV-2 can be blocked by engineered S1-RBD fraction	10
Quantum study of symmetrical/asymmetrical charge and energy transfer in a simple candidate molecular switch	10
J. Fraser Stoddart (1942–2024) Nobel laureate for molecular machines—author in Structural Chemistry	10
Hybrid drug-screening strategy identifies potential SARS-CoV-2 cell-entry inhibitors targeting human transmembrane serine protease	10
Computational analysis of chalcogen-enhanced triphenylamine–based D-π-A sensitizers for DSSCs: a DFT study	10
Structure–antioxidant activity (oxygen radical absorbance capacity) relationships of phenolic compounds	10
Template syntheses, molecular structures, and antimicrobial activities of two novel Schiff-base macrocyclic lanthanide complexes	10
Synthesis, crystal structure, Hirshfeld surface analysis, and DFT studies of 2-bromo-4,6-bis(dibromoacetyl)resorcinol	10
Acid-based analogs of certain water tetramers: an examination of some crystal structures in the literature	9

Crystal structure and triboluminescence of europium(III) tetrakis-thenoyl trifluoroacetonate with outer-sphere organic cation	9
Theoretical insights into the structural and magnetic properties of trimetallic Ni-Co–Rh nanoalloys	9
Remembering Alan L. Mackay (1926–2025)—a scientists’ scientist in the footsteps of Lucretius	9
Crystal structure, supramolecular framework, hirshfeld surface analysis, and photophysical studies of some acridinium/acridine derivatives prepared by mechanochemical synthesis	9
Integrated computational approach towards repurposing of antimalarial drug against SARS-CoV-2 main protease	9
The quadruple bond – 60 years – a tribute to F. Albert Cotton and other pioneers	9
Kai M. Siegbahn (1918‒2007): a pioneer in high-resolution electron spectroscopy	9
A DFT study on the Sc(OTf)3 catalyzed hetero Diels–Alder reaction of N-tosylhydrazones and ortho-quinone methides: energetic aspects, selectivities, and molecular mechanism	9
Nickel(II) complexes with a tetraazamacrocyclic diene ligand and its isomeric 'ane' forms: Synthesis, characterization, and antibacterial activities	9
Preparation and characterization of l-cystinium(2+) bis-iodide monohydrate and l-cystinium(2+) bis-triiodide	8
Theoretical studies on the mechanism, kinetics, and degradation pathways of auxin mimic herbicides by •OH radical in aqueous media	8
A computational study of potential therapeutics for COVID-19 invoking conceptual density functional theory	8
Theoretical study on the isomerization mechanism of azobenzene derivatives on graphene substrate	8
Investigation of typical heterocyclic fragment structures and reaction characteristics in oil shale using density functional theory	8
A comprehensive exploration of pharmacological properties, bioactivities and inhibitory potentiality of luteolin from Tridax procumbens as anticancer drug by in-silico approach	8
Thermochemistry of monocharged cation substitutions in ionic solids	8
Thermochromic photoluminescence of phosphine-supported dinuclear copper‒halide complexes	7
The influence of structural isomerism on luminescence properties of [Re(CO)2(dppv)(pbi)] complexes containing cis-1,2-bis(diphenylphosphino)-ethene and 2-(2-pyridyl)benzimidazole ligands	7
Impact of chlorine substitution on supramolecular architecture and non-covalent interactions in Ethyl 2-amino-6-chloro-4-aryl-7-hydroxy-4H-benzo[4,5-e]pyran-3-carboxylate Isomers: a combined experimen	7
Theoretical investigation on the effect of additional hydrogen bonded network on the ground state double proton transfer of 2-aminopyrazine-H2O compound	7
A DFT study of antioxidant potential of vanilla seed extracts by double H + /e − mechanism	7
Exploration of the mechanism of the condensation reaction of Al(OH)4− with a D-gluconate using density functional theory	7
Chemical structure and its evolution in terms of the superimposed electrostatic, exchange, and total static force fields, and the role of the electronic forces in atomic charge redistribution	7
Exploration of chalcones as 3-chymotrypsin-like protease (3CLpro) inhibitors of SARS-CoV-2 using computational approaches	7
Designing multi-epitope based peptide vaccine targeting spike protein SARS-CoV-2 B1.1.529 (Omicron) variant using computational approaches	7
Reversible coloring/decoloring reactions of thermochromic leuco dyes controlled by a macrocyclic compound developer	7
Density functional theory study on the reaction mechanism of Ni+-catalysed cyclohexane dehydrogenation	7
A series of cannabinoids including, cannabidiol, cannabigerol, cannabichromene, and Δ8- and Δ9-tetrahydrocannabinol are estimated using synthetic and retrosynthetic analysis, group additivity, and exp	7
Structure–antioxidant activity relationships of dendrocandin analogues determined using density functional theory	7
Synthesis, characterization, solvatochromic, and electrochemical investigation of novel 4-methyl coumarin fused azo dyes as an NLO material and their biological studies	7
Structural and energetic effect of the intramolecular hydrogen bonding in 4,6-dihaloresorcinols: ab initio calculation, vibrational spectroscopy, and molecular docking studies	7
Exploring the effect of complexant on remarkably high static and dynamic second hyperpolarizability of aziridine-based diffuse electron systems: a theoretical study	7
Quantum chemical evaluation, ELF, LOL analysis, Fukui, herbicide-likeness and molecular docking studies of 4-methyl-phenoxyacetic acid, 4-acetyl-phenoxyacetic acid and 4-tert-butyl-phenoxyacetic acid	7
Molecular and electronic structures, bonding analysis, and UV–Vis spectra predictions of quinolino[3,2-b]benzodiazepine and quinolino[3,2-b]benzoxazepine metal transition M(L)2Cl2 and M(L)Cl2 complexe	7
Stabilization of cyclo-N6 by insertion into [18]-annulene: a DFT study	7
Multiple 3D- and 2D-quantitative structure–activity relationship models (QSAR), theoretical study and molecular modeling to identify structural requirements of imidazopyridine analogues as anti-infect	7
Unfolding of an alpha-helical peptide exposed to high temperature: suggesting a critical residue in the process	7
Solvent assisted synthesis and characterization of 2D and 3D cadmium metal–organic framework	7
Ab initio studies on complexes of ozone with diatomic molecules	7
First-principles study of dynamic symmetry in acrylic acid	7
Metal cyamelurates: structural diversity caused by kinetic and thermodynamic controls	7
Adsorption behavior of hydrogen selenide gas on the surfaces of pristine and Ni-doped X12Y12 (X=Al, B and Y=N, P) nano-cages: a first-principles study	7
Role of central core and methyl substitutions in XH4-x(CH3)x (X = N, P, As; x = 0–4) superalkalis: an ab initio study	6
Synthesis and structural characterization of new layered hydroselenites (enH2)[Ni(HSeO3)2Br2] and (dmedaH2)[Ni(HSeO3)2X2], X = Cl, Br	6
Optical and electronic properties of para-functionalized triphenylamine-based dyes: a theoretical study	6
Initiating a new column: Foundation of structural science	6
Theoretical investigation of Br2 and Cl2 detection by the pristine and Co-doped graphyne	6
Experimental and computational investigations of two N′-(adamantan-2-ylidene)-substituted benzohydrazide derivatives: crystal structures, antiproliferative activity, molecular docking, and molecular d	6
Interactions between favipiravir and a BNC cage towards drug delivery applications	6
How physicists became biologists	6
Donald L.D. Caspar (1927–2021)—pioneer of virus structures	6
DFT/TD-DFT investigation of novel D–π–A configuration dyes for improving solar cell efficiency	6
A comparative DFT study on antioxidative activity of 3- and 4-phenylcoumarins: an aspect of structure, electronics, mechanism, kinetics, and metal chelate relations	6
Features of contraction of solids: cooling vs pressing	6
Pharmacokinetics and molecular docking of novel antineoplastic sesquiterpene lactone from Tarchonanthus camphoratus L: an in silico approaches	6
Complexation behaviour of piceatannol ligand with Ti(IV) and Zr(IV) metal ions: a combined DFT and deep learning investigation	6
Small molecule activation and dehydrogenation of an amine–borane system using frustrated Lewis pairs	6
Density functional theory investigation of interactions between phenolic compounds and water or hydrophobic deep eutectic solvent	6
Graphene oxide and flavonoids as potential inhibitors of the spike protein of SARS-CoV-2 variants and interaction between ligands: a parallel study of molecular docking and DFT	6
Gas-phase 2-hydroxypyridine/2-pyridone system: temperature dependence of fractions retrieved from electron diffraction data	6
Paradoxes and paradigms: the stabilization/resonance energy of some –C(O)– species: acetyl derivatives, metal carbonyls, and amides alike	6
Quantum-chemical study of organic reactions mechanisms	6
The first examples of nitrobenzoate coordinated ruthenium(II) organometallics: reaction conditions driven product formation	6
A computational DFT insight into adsorption properties of urea and creatinine molecules on pristine B24O24 nanocluster	6
Electronic structure of curcuminoids with potential medicinal applications: a theoretical insight	6
Gas-phase acidities of organic acids based on 9H-fluorene scaffold: a DFT study	6
Evolution detection of phenol by pristine BN nanocone: chemical quantum study	6
New carbazole-based dyes for efficient dye-sensitized solar cells: a DFT insight	6
Computational study of the bonding in η3-propargyl complexes of platinum and related species using MO, NBO, and QTAIM analysis	6
Theoretical evaluation of Al-doped biphenylene nanosheet sensing properties toward gamma-butyrolactone	6
A quantum chemical approach to the physical interpretation of the classical substituent effect in the 2,4-diaryl-4H-1,4-thiazine derivatives	6
Tuberculosis and HIV responses threatened by nCOVID-19: A situation prompting an in silico investigation of reported MbtA inhibitors for combined inhibition of SARS-CoV-2 and HIV-TB co-infection	6
Antioxidant activities of Alyssum virgatum plant and its main components	6
A simplistic computational procedure for tunneling splittings caused by proton transfer	5
Nickel(II) complexes with 2-aminomethylbenzimidazole: crystal structures and Hirshfeld surface analysis	5
Theoretical aspects of interaction of the anticancer drug cytarabine with human serum albumin	5
A proposed process for trichlorfon and β-cyclodextrinInclusion complexation by DFT investigation	5
Molecular and supramolecular structures of new 5-phenyl-1H-pyrrol-2-carbonyl azide	5
In pursuit of novel pyriporphyrin—a porphyrin ring expansion congener containing a built-in pyridine moiety by CH radical: a DFT investigation	5
A computational perspective on the changes made in the structural, optical, and electronic properties of melamine and picric acid/quinol with the formation of charge transfer complexes	5

Consecutive Friedel–Crafts acyl rearrangements and Scholl reactions of dinaphthyl ketones	5
Enhanced antioxidant properties of novel curcumin derivatives: a comprehensive DFT computational study	5
150 years of stereochemistry—selected examples	5
Exploring the adsorption performance of doped graphene quantum dots as anticancer drug carriers for cisplatin by DFT, PCM, and COSMO approaches	5
Atomic and molecular volumes from three crystal tessellations: a comparison of the QTAIM, Hirshfeld, and Voronoi data	5
Reminiscing about Ron Gillespie	5
Revealing the cyclization selectivity in intramolecular [3 + 2] cycloaddition reactions of allenic nitrones from the molecular electron density theory perspective	5
Benzothiazole and benzoxazole promoted cleavage of Ru − C(aryl) bond in a four-membered ortho-metalated ruthenium(II) organometallics	5
In vitro antioxidant activities of five β-carboline alkaloids, molecular docking, and dynamic simulations	5
Electronic and optical properties of C60 under the influence of alkali metal injection: A DFT study	5
David Harker—a life for crystallography	5
Semi-coordination Cu–O bond on a copper complex featuring O,O-donor ligand as potential antibacterial agent: green synthesis, characterization, DFT, in-silico ADMET profiling and molecular docking stu	5
Vertexane and related molecules: a computational exploration with contemporary quantum chemistry methods	5
Anticancer effects of dendrocandin (DDCD) against AKT in HepG2 cells using molecular modeling, DFT, and in vitro study	5
Study of heteroatom-doped graphene properties using DFT/TD-DFT, QTAIM, NBO, and NCI calculations	5
Synthesis, crystal structure, and biological activity of menthol-based chiral quaternary phosphonium salts (CQPSs)	5
Features of molecular structures of some IPR isomers of C96 fullerene	5
Paradoxes and Paradigms: elements and compounds: similar names, very different energetics	5
Rudolph A. Marcus at 100 – theoretician of electron transfer reactions	5
Crystal structure of (Z)-10-(bromoiodomethylene)phenanthren-9(10H)-one: halogen bond and mechanism implication	5
Synthesis of 3,4-dihydro-1,3,5-triazin-2(1H)-one derivatives by recycling 2H-1,3,5-oxadiazine-2,4(3H)-diimines: their spectral characteristics and molecular structure	5
Si(IV) cationic superalkalis: [SiCl3(LR3)2]	5
DFT study of Pt-rGO as a potential catalyst for glycerol hydrodeoxygenation into propanediols	5
Harnessing data science to improve molecular structure elucidation from tandem mass spectrometry	5
Identification of potent, non-toxic, selective CDK2 inhibitor through the pharmacophore-based scaffold hopping, molecular dynamics simulation-assisted molecular docking study, Lee Richard contour map	4
Bruce Merrifield centennial: pioneer of chemical synthesis on solid matrix	4
A robust three-component synthesis of dispiroheterocycles containing aurone scaffold via 1,3-dipolar cycloaddition reaction of azomethine ylides: regioselectivity and mechanistic overview using DFT ca	4
On using DFT to construct an IR spectrum database for PFAS molecules	4
A DFT study of the adsorption of vanillin on Al(111) surfaces	4
Dynamic stereochemistry at work: Configurational lability of nitrogen and sulfur atoms within a sulfonamide moiety as a cause of forming supramolecular diastereomers in crystals	4
Unveiling [3 + 2] cycloaddition reactions of pyridinium bis(methoxycarbonyl)methylides and pyridinium dicyanomethylides with cyclooctyne for indolizine synthesis from the molecular electron density th	4
Studying the impact of NCS− anion and the steric hindrance of flexible N-donor ligands on the crystal engineering of the mercury(II) coordination polymer	4
Computational studies on transition metal and nitrogen atoms co-doped fullerene as an efficient electrocatalyst for nitrate reduction to ammonia	4
Identification of multi-targeting natural antiviral peptides to impede SARS-CoV-2 infection	4
Synthesis, XRD structure, spectroscopy, hirshfeld surface analysis, and computational and in silico ADME studies of 13-(piperidinyl)parthenolid-9-one	4
Identification, virtual screening and molecular dynamic analysis of novel TMPRSS2 inhibitors from natural compound database as potential entry-blocking agents in SARS-CoV-2 therapy	4
Novel pull–push solar switches with a D-π-D-π-A framework of the thiophene core: computed absorbance/fluorescence ability with device parameters	4
Optimization, spectral characterization, QSAR, and molecular docking analyses of newly designed boron compounds	4
Asymmetrical curcumin derivative: synthesis, structural exploration, Hirshfeld surface analysis, and computational study	4
In silico investigations of high-energy density properties and effect of ring fusion on dinitropyrazole derivatives	4
Size of isolated atoms	4
Eugene Garfield (1925 − 2017)—a high-impact information scientist	4
Functional roles of the electronic force fields in supramolecules and molecular crystals. Estimating the exchange-force component contributions from the inner-crystal electron density	4
The “reaction zone” concept in modeling solid-state transformations and predicting crystal structures	4
Design, synthesis, and theoretical analysis of anthracene-based sensitizers for enhanced dye-sensitized solar cell efficiency	4
Theoretical studies on the effects of solvents on the mechanisms of configuration transformation of ε-CL-20	4
DFT studies on the physicochemical properties of a new potential drug carrier containing cellobiose units and its complex with paracetamol	4
Quantum mechanical modeling unveils the effect of substitutions on the activation barriers of the Diels–Alder reactions of an antiviral compound 7H-benzo[a]phenalene	4
Structures and energetics of darunavir and active site amino acids of native and mutant HIV–1 protease: a computational study	4
Piperazine-thiophene hybrid as a promising SGLT2 inhibitor: insights from DFT and molecular docking studies	4
Bimetallic doping of benzocryptand with alkaline earth metals for outstanding nonlinear optical response; a DFT study	4
Correction to: Determination of dissociation constants of cephalosporin antibiotics by cellmetry method	4
Crystal structure, Hirshfeld surface analysis, and DFT theoretical studies of an azobenzene derivative from powder X-ray diffraction	4
The dubious origin of beryllium toxicity	4
Solvent-assisted investigation of NLO responses of 3,5-dihydroxybenzoic acid and pyrazine-2-carboxamide cocrystal	4
A new contribution to the lead and strontium perrhenate chemistry: Synthesis and crystal structures of Pb(ReO4)Cl·2H2O, Pb(ReO4)2·2H2O, {Pb4(OH)4}(ReO4)4·H2O, Sr(ReO4)2·H2O, and Sr(ReO4)2·6H2O	4