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Abstract In this study, the chemoselective synthesis of two new thiophene derivatives is presented. The structure of newly synthesized thiophenes derivatives; ethyl 4-acetyl-3-phenyl-5-(phenylamino)thiophene-2-carboxylate (5) and ethyl (E)-4-(3-(dimethylamino)acryloyl)-3-phenyl-5-(phenylamino)thiophene-2-carboxylate (8) were established using different FTIR and NMR spectral analyses. Compound 8 was isolated as single crystal and its 3D structure was determined using X-ray crystallographic analysis. Possible intermolecular interactions that control the molecular packing of 8 were elucidated using Hirshfeld topology analysis. The O…H (13.7%), H…H (55.3%) and C…C (2.3%) intermolecular interactions are the most significant. Fukui functions showed that C4 in thiophene 5 and C3 in thiophene 8 are the most reactive atoms for nucleophilic attack, while N9 in thiophene 5 and C1 in thiophene 8 are the most reactive atoms for electrophilic attack. Antitumor activity of thiophene 5 was assessed and the results showed higher activity against HepG-2 (7.46 µg/mL) compared to the HCT 116 (12.60 µg/mL) cell line.

Three amidine-based ligands were used in the crystal design of a series of mononuclear Zn(II) complexes. Interaction of zinc chloride, ZnCl2, with N-2-pyridylimidoyl-2-pyridylamidine (Py2ImAm) resulted in complexes [Zn(Py2ImAm)2] (1) and [ZnCl2(Py2ImAm)] (2). In [Zn(Py2ImAm)2] (1, monoclinic, P21/c), the metal ion was coordinated with the bidentate pocket of the anionic form of Py2ImAm, while in [ZnCl2(Py2ImAm)] (2, monoclinic, P21/n), the tridentate coordination to a neutral Py2ImAm was completed by two chloride anions. This structural variation was achieved by a pH-controlling strategy using the weak base triethylamine (TEA). Otherwise, three ionic complexes were obtained with 2-amidinopyridine (PyAm) and Zinc(II), [ZnCl(PyAm)2]Cl (3, triclinic, P-1), [ZnCl(PyAm)2]2[ZnCl4]·C2H5OH (4, monoclinic, P21/n), and [ZnCl(PyAm)2]2Cl·CH3OH (5, triclinic, P-1). They comprised the same [ZnCl(PyAm)2]+ monocation with a butterfly-like shape provided by the bidentate chelate coordination of two PyAm neutral entities and a chloride ligand. In a similar butterfly shape, ionic complex [ZnCl(PmAm)2]2[ZnCl4] (6, monoclinic, C2/c) comprised the mononuclear [ZnCl(PmAm)2]+ cations with two bidentate chelate-coordinated 2-amidinopyrimidine (PmAm) as neutral ligands. The Zn(II) pentacoordinated arrangement in 3–6 was variable, from square pyramidal to trigonal bipyramidal. The reported compounds’ synthetic protocols, crystal structures and photoluminescence properties are discussed.

Abstract Cyclooctatetraene (COT) and COT2− dianion are well‐known as archetypical non‐aromatic and aromatic systems, respectively. However, despite a wealth of studies the effect of one electron addition to the eight‐membered ring remains equivocal. Herein, we report the first stepwise electron addition to tetrabenzo[a,c,e,g]cyclooctatetraene (TBCOT or tetraphenylene), accompanied by isolation and structural characterization of the mono‐ and doubly‐reduced anions. The X‐ray crystallographic study reveals only a small asymmetric distortion of the saddle‐shaped core upon one electron uptake. In contrast, the doubly‐reduced product exhibits a severely twisted conformation, with a new C−C bond separating the COT ring into two fused 5‐membered rings. The reversibility of the two‐fold reduction and bond rearrangement is demonstrated by NMR spectroscopy. In agreement with experimental results, computational analysis confirms that the reduction‐induced core rearrangement requires the addition of the second electron.

Summary: Alkynes are widely present in natural products and pharmaceutical compounds. Here, we present a protocol for nickel-catalyzed cross-coupling of terminal alkynes with aryl iodides or bromides for constructing a C(sp2)-C(sp) bond. We describe steps for reagent preparation, reaction setup, purification process, and product characterization. We also detail procedures for obtaining a single crystal of 6-(phenylethynyl)-1-(phenylsulfonyl)-1H-indole (3b). The application of this protocol is limited to aryl bromide and iodide.For complete details on the use and execution of this protocol, please refer to Chen et al.1 : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

A heterometal assembled complex of tetrakis(μ-butanoato)diruthenium(II,III) and tetracyanidoaurate(III) [RuIIRuIII(n-C3H7COO)4AuIII(CN)4]n was synthesized and characterized by the elemental analysis and infrared spectroscopy. The single-crystal X-ray structure analysis revealed that the complex consists of zigzag chain molecules of alternating arrangement of the Ru2(n-C3H7COO)4+ and Au(CN)4– units with cis-bridging mode of the Au(CN)4– units. The temperature dependence of the magnetic susceptibility data (4.5—300 K) showed that the magnetic interaction between the dinuclear RuIIRuIII units (S= 3/2) is negligibly small with a zero-field splitting parameter D value of 60 cm-1.

The transition-metal free S-vinylation of thiophenols by vinylbenziodoxolones (VBX) constituted an important step forward in hypervalent iodine-mediated vinylations, highlighting the difference to vinyliodonium salts and that the reaction outcome was influenced by the substitution pattern of the benziodoxolone core. In this study, we report several new classes of hypervalent iodine vinylation reagents; vinylbenziodazolones, vinylbenziodoxolonimine and vinyliodoxathiole dioxides. Their synthesis, structural and electronic properties are described and correlated to the S-vinylation outcome, shedding light on some interesting facets of these reagents.

Specific rotation of optically active glycerol analogues, (S)-3-(benzyloxy)propane-1,2-diol [(S)-1], (S)-3-methoxypropane-1,2-diol [(S)-6] and (S)-3-phenoxypropane-1,2-diol [(S)-13], changed its sign from (+) to (–) with increasing concentration in CHCl3, whereas no significant concentration-dependent change was observed in MeOH. The 1H NMR spectrum of (S)-1 showed concentration-dependent changes of the chemical shift in CDCl3. Intermolecular interaction by OH⋯OH hydrogen bonds was suggested by single crystal X-ray crystallography of (S)-13. The concentration-dependent changes of specific rotation of (S)-1, (S)-6, and (S)-13 in CHCl3 can therefore be presumed to be due to self-assembly of these compounds via intermolecular hydrogen bonding at high concentration. The remarkable concentration-dependent changes in specific rotation were also observed to occur in the compounds with related chemical structures, such as (S)-3-hydroxy-4-methoxy-4-oxobutanoic acid [(S)-10], (S)-1-[(2-methylpropan-2-yl)oxycarbonyl]pyrrolidine-2-carboxylic acid [Boc-L-Pro-OH, (S)-14], (R)-3-hydroxy-4,4-dimethylhydrofran-2(3H)-one [(R)-15], (R)-tetrahydrofuran-2-carboxylic acid [(R)-16], (S)-3-methyl-2-[(2-methylpropan-2-yl)oxycarbonylamino]butanoic acid [Boc-L-Val-OH, (S)-17], (R)-oxiran-2-ylmethanol [(R)-18], and (4S)-4-isopropyloxazolidin-2-one [(S)-19]. The existence of intermolecular interaction by C=O⋯HO hydrogen bonds was suggested by single crystal X-ray crystallography of (S)-10, (S)-13, and (S)-14. Thus, this series of chiral compounds have multiple functional groups in appropriate positions that serve as hydrogen-bond donors and/or acceptors, resulting in significant concentration-dependent changes of specific rotation.

Photochromic fluorescent proteins (FPs) have proved to be indispensable luminous probes for sophisticated and advanced bioimaging techniques. Among them, an interplay between photoswitching and photoconversion has only been observed in a limited subset of Kaede-like FPs that show potential for discovering the key mechanistic steps during green-to-red photoconversion. Various spectroscopic techniques including femtosecond stimulated Raman spectroscopy (FSRS), X-ray crystallography, and femtosecond transient absorption were employed on a set of five related FPs with varying photoconversion and photoswitching efficiencies. A 3-methyl-histidine chromophore derivative, incorporated through amber suppression using orthogonal aminoacyl tRNA synthetase/tRNA pairs, displays more dynamic photoswitching but greatly reduced photoconversion versus the least-evolved ancestor (LEA). Excitation-dependent measurements of the green anionic chromophore reveal that the varying photoswitching efficiencies arise from both the initial transient dynamics of the bright cis state and the final trans-like photoswitched off state, with an exocyclic bridge H-rocking motion playing an active role during the excited-state energy dissipation. This investigation establishes a close-knit feedback loop between spectroscopic characterization and protein engineering, which may be especially beneficial to develop more versatile FPs with targeted mutations and enhanced functionalities, such as photoconvertible FPs that also feature photoswitching properties.

Stable ylide of di-tert-butyl-2-(2-indolinon-1-yl)-3-(trimethoxyphosphorane ylidene) butanedioate was synthesized by means of catalyst-free reaction of trimethyl phosphite, di-tert-butylacetylene dicarboxylate and 2-indolinone in n-hexane/diethyl ether at ambient temperature. Obtained product was characterized by 1H, 13C, 31P NMR, FT-IR and mass spectroscopy. The crystal structure of the stable ylide was determined by X-ray crystallography. The title compound crystallized in monoclinic, space group P21/c and cell parameters a=15.8079(7) Å, b= 18.7521(13) Å, c =17.4987(10) Å, β= 95.504(6)° and Z=8. The X-ray study showed that adjacent carbonyl group (C291=O291, C191=O191) in the ylide moiety of compound had a resonance with bond of C=P. These results show clearly that environment of C(19, 29) is planar.

The condensation product of 7-acetyl-6-azaindole and Girard’s T reagent ((E)-2-(2-(1-(1H-pyrrolo[2,3-c]pyridin-7-yl)ethylidene)hydrazineyl)- -N,N,N-trimethyl-2-oxoethan-1-aminium, HL ligand) was used as a ligand in the reaction with Cu(BF4)2·6H2O and NaN3. The reaction led to the formation of a binuclear Cu(II) complex containing two end-to-end (di-μ-1,3-N3) azide bridges, as well as two NNO-donor hydrazone ligands, forming an axially elongated square pyramidal geometry around each Cu(II) center. This end-to-end (di- μ-1,3-N3) azide bridge binding mode has not yet been reported, in Cu(II) complexes containing the NNO-donor hydrazone ligands, which makes the structure of the complex even more interesting for further studies. The complex was characterized by elemental analysis, IR spectroscopy and X-ray crystallography, and it was found that it crystallizes in the triclinic space group P–1 with the asymmetric unit comprising one Cu(II) centre, zwitterionic ligand L, one azide (N3 -) ligand and BF4 - counter anion. Examination of antimicrobial activity of the complex shows higher antifungal and antibacterial activity towards tested Gram-positive bacteria in comparison to the hydrazone ligand, with the antifungal activity of the complex even being comparable to the activity of amphotericin B.

The synthesis, structural analysis and spectroscopic characterisation of three new 7-azaindole ligands is reported, alongside a novel 7-azaindole derived coordination polymer, with the aim of identifying new bridging ligands containing inner-sphere hydrogen bond donor functionality. Structural characterisation shows that the 7-azaindole hydrogen bond donor ability is significantly stronger in the hydrazone and imine species 1 and 2 compared to the amine 3, with the opposite trend evident in their hydrogen bond acceptor character. These findings are mirrored by the fluorescence spectroscopy results which show bimodal emission, characteristic of multiple emissive species related by proton transfer, is only evident in the amine species and not the more acidic imines. The polymeric copper(II) complex of the hydrazone ligand 1 shows the anticipated inner-sphere hydrogen bonding with a similar donor strength to that observed in the free ligand, which leads to deformation in the remainder of the coordination sphere. These results show the untapped versatility of the 7-azaindole functional group as a building block for ligands in coordination polymers and other multinuclear assemblies, with the potential for both stabilisation through hydrogen bonding and interesting photophysical properties.

Two coordinating compounds of zinc(II) (1) [Zn2(DAnH2)2(1,3-bdc)2(DMSO)4] and nickel(II) (2) [Ni(DAnH2)(1,4-bdc)(DMF)2]n were obtained based on dianilineglyoxime (DAnH2), 1,3-benzenedicarboxylic acid (1,3-bdcH2) and 1,4-benzenedicarboxylic acid (1,4-bdcH2), where DMSO is dimethylsulfoxide and DMF is dimethylformamide. The molecular and crystalline structure of reported compounds were established by infrared spectroscopy and single crystal X-ray diffraction, and for 1, additionally, the 1H and 13C NMR spectroscopy was used. According to data, the Zn(II) molecular complex is a binuclear and the Ni(II) is a 1D polymer compound.

The reaction of 2,2-dimethylpropane-1,3-diamine (dmpn) with an excess of concentrated aqueous hydrochloric acid yielded colorless crystals of 2,2-dimethylpropane-1,3-diaminium dichloride, dmpnH2Cl2 (1), in addition to small amounts of a monohydrate, dmpnH2Cl2∙H2O (2). The compounds were studied via X-ray crystallography, IR and Raman spectroscopy, NMR spectroscopy and thermal analysis. Single crystal structure determinations on 1 and 2 showed that dmpnH2Cl2 exists in two polymorphic forms, 1a and 1b. The crystal structure of 1b showed to be much more complex than that of 1a. In the crystal structure of 2, four (dmpnH2)2+ cations and eight chloride anions form a cage constructed by N−H∙∙∙Cl hydrogen bonds. In the center of these cages water dimers with a O∙∙∙O distance of 2.776 (8) Å are present. In addition, a conformational analysis of the 2,2-dimethylpropane-1,3-diaminium cation was performed. The results are compared to the experimental findings of 1a, 1b, 2 and other related hydrogen bonded salt structures from the Cambridge crystallographic structure database (CCDC). Last, a topological classification of the solid-state structures of 1a and 2 was performed and the simplified topological networks are discussed.

Utilizing X-ray crystallography, the crystal and molecular structures of 2,6-diacetylpyridine bis(phenylhydrazone) (L) were determined. The energetics of the intermolecular interactions in the crystal structure were assessed with computational methods, revealing that dispersion interactions are dominant. The basic structural unit of the crystal packing was revealed to be the herring- bone type arrangement of L molecules. Assignation of the IR spectrum of L with the aid of DFT calculations was performed. Furthermore, new reactions of L with CuBr2 in different solvents are described, which led to the synthesis of the mixed Cu(II)–Cu(I) complex with the formula [CuIIL2][CuI 2Br4] (1), and its structural characterization. In the complex cation, two molecules of tridentate N3 ligand are meridionally arranged in a very distorted octahedral environment of a Cu(II) ion. In [Cu2Br4]2-, the bromide ions are arranged in a trigonal- -planar geometry around each copper(I) atom. Finally, for ligand, 1, and the previously synthesized complex [CuL2]Br2, the thermal properties were examined. The thermal stability of the complexes were lower than that of the ligand and decrease in the order: L (250°C) > [CuL2]Br2 (221°C) > [CuIIL2][CuI 2Br4] (212°C). The differences in thermal stability of the complexes are due to differences in the packing efficacy of the constitutional ions.

The development of efficient methods for the synthesis of polyfunctional N-heterocycles is an important area of research in organic and medicinal chemistry. Pyrazolo[1,5-a]pyrimidine derivatives are purine analogous of biomedical importance and have been extremely studied for their broad spectrum of biological activities. Recently, they have attracted great interest in materials science owing to their photophysical properties. 3(5)-Aminopyrazoles are extensively utilized in the synthesis of condensed heterocyclic systems, particularly pyrazolo[1,5-a]pyrimidines via the reaction with 1,3-biselectrophilic reagents. However, the information available in the literature provides little in the way of reasoning their cyclization, particularly the initial attack either by the exocyclic amino group or endocyclic nitrogen. Unfortunately, the relative nucleophilicity of exo- and endocyclic nitrogen atoms in 1-unsubstituted 3(5)-aminopyrazoles is not clear and contradicting. It has been found that other factors can modulate the regioselectivity rather than basicity or steric hindrance for both active sites. The reported studies in the structure–activity relationship revealed that pyrazolo[1,5-a]pyrimidines having a substitution at fifth, sixth, and seventh positions possess potent biological activities, especially those with an amino group at the seventh position. We here developed a regioselective, high yield synthesis of 7-amino-5-arylpyrazolo[1,5-a]pyrimidine-3,6-dicarbonitriles by the reaction of N-(5-amino-4-cyano-1H-pyrazole-3-yl)-benzamide with various cinnamonitriles and enaminones in pyridine at 120°C under controlled microwave heating conditions. All structures of newly synthesized compounds were established by analytical and spectral data as well as single-crystal diffraction and rationalized for their formation.

Abstract Oxidative condensation of three p‐phenylenediamines with 3‐hydroxy‐2‐methyl‐N‐(phenylamino)benzene gives new coloured aposafranones. 2‐Methylresorcinol is easy to convert into the asymmetric building block 3‐hydroxy‐2‐methyl‐N‐(phenylamino)benzene with aniline. The aposafranones are sterically crowded because of the 1‐methyl and N‐phenyl groups. The UV/Vis absorption maxima are in the range 530–545 nm.

The novel Schiff base, (E)-4-((2-hydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (L1), and its mixed ligand complexes with 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine as an auxiliary ligand (L2) and different transition metal ions (Mn(II), Fe(III), Co(II), Ni(II), Zn(II) and Cd(II)) were synthesised. The 1H NMR spectra of L1 supported their geometrical structures, which was confirmed by X-ray crystallography. The packing of L1 is dominated by H…H, O…H, H…C, C…C, C…N, C…O and N…H interactions. Density functional theory (DFT) calculations showed excellent straight-line correlations between the calculated and experimental geometric parameters where the most stable isomer of L1 is stabilised by an OH…N hydrogen bond, and which agrees with the reported X-ray structure. The prepared complexes were characterised by elemental analyses, molar conductance measurements, IR, UV–vis, and 1H NMR spectroscopic methods. The elemental analysis data suggested a 1:1:1 [M:L1:L2] ratio for all the complexes. The molar conductance measurements of the complexes indicate their electrolytic nature in DMSO as solvent. The electronic absorption spectral data revealed the existence of an octahedral geometry for all complexes.

This review focuses on the synthesis, structural characterization, and biological activity of organotin complexes with drug such as non-steroidal anti-inflammatory drugs (NSAIDs)/quinolones. Organotin complexes have been widely studied due to their potential pharmacological applications, and the combination with drug provides an interesting approach for the development of new therapeutic agents. The review covers recent advances in the synthesis and characterization of organotin-NSAID/Quinolonescomplexes, including their spectroscopic and crystallographic properties with the help of X-ray crystallography. Moreover, the biological activity of these complexes is discussed, with a particular focus on their potential anti-inflammatory, anticancer, and antimicrobial properties. Results pertaining to the biological activities of these organotin complexes have been mentioned. The review highlights the importance of organotin complexes with NSAID/Quinolones in medicinal chemistry and the need for further studies to explore their potential as therapeutic agents.

Abstract Six bile acid alkyl amide derivatives were studied with respect to their gelation properties. The derivatives were composed of three different bile acids with hexyl or cyclohexyl side chains. The gelation behaviour of all six compounds were studied for 36 solvents with varying polarities. Gelation was observed mainly in aromatic solvents, which is characteristic for bile‐acid‐based low molecular weight gelators. Out of 108 bile acid‐solvent combinations, a total of 44 gel systems were formed, 28 of which from lithocholic acid derivatives, only two from deoxycholic acid derivatives, and 14 from cholic acid derivatives. The majority of the gel systems were formed from bile acids with hexyl side chains, contrary to the cyclohexyl group, which seems to be a poor gelation moiety. These results indicate that the spatial demand of the side chain is the key feature for the gelation properties of the bile acid amides.

A series of three new hydrazone compounds derived from the condensation reactions of 4-dimethylaminobenzohydrazide with 4-dimethylaminobenzaldehyde, 2-chloro-5-nitrobenzaldehyde and 3-methoxybenzaldehyde, respectively, were prepared. The compounds were characterized by elemental analysis, infrared and UV-vis spectra, HRMS, 1H NMR and 13C NMR spectra, and single crystal X-ray diffraction. Crystals of the compounds are stabilized by hydrogen bonds. The compounds were assayed for antibacterial (Bacillus subtilis, Escherichia coli, Pseudomonas fluorescence and Staphylococcus aureus) and antifungal (Aspergillus niger and Candida albicans) activities by MTT method. The results indicated that compound 2 is an effective antibacterial material.

Small functional siloxane units have gained great interest as molecular model systems for mimicking more complex silicate structures both in nature and in materials chemistry. The crystal structure of chloropentaphenyldisiloxane, which was synthesized for the first time, was elucidated by single-crystal X-ray diffraction analysis. The molecular crystal packing was studied in detail using state-of-the-art Hirshfeld surface analysis together with a two-dimensional fingerprint mapping of the intermolecular interactions. It was found that the phenyl C–H bonds act as donors for both weak C–H···π and C–H···Cl hydrogen bond interactions. The influence of intramolecular Si–O–Si bond parameters on the acceptor capability of functional groups in intermolecular hydrogen bond interactions is discussed.

N,N′,N″,N‴-Tetraisopropylpyrophosphoramide 1 is a pyrophosphoramide with documented butyrylcholinesterase inhibition, a property shared with the more widely studied octamethylphosphoramide (Schradan). Unlike Schradan, 1 is a solid at room temperature making it one of a few known pyrophosphoramide solids. The crystal structure of 1 was determined by single-crystal X-ray diffraction and compared with that of other previously described solid pyrophosphoramides. The pyrophosphoramide discussed in this study was synthesised by reacting iso-propyl amine with pyrophosphoryl tetrachloride under anhydrous conditions. A unique supramolecular motif was observed when compared with previously published pyrophosphoramide structures having two different intermolecular hydrogen bonding synthons. Furthermore, the potential of a wider variety of supramolecular structures in which similar pyrophosphoramides can crystallise was recognised. Proton (1H) and Phosphorus 31 (31P) Nuclear Magnetic Resonance (NMR) spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS) were carried out to complete the analysis of the compound.

Abstract A microwave‐based methodology facilitates reaction of 2‐aminophenylketones with cyclic ketones to form a quinoline scaffold. Syntheses of amido‐ and amino‐linked 17β‐hydroxysteroid dehydrogenase type 3 inhibitors with a benzophenone‐linked motif were pursued using 2‐aminobenzophenone as building block. Two amido‐linked targets were achieved in modest yield, but when using microwave‐assisted reductive amination for the amino‐linked counterparts an unexpected product was observed. X‐ray crystallography revealed it as a quinoline derivative, leading to optimisation of a simple and efficient modification of Friedländer methodology. Using reagents and acetic acid catalyst in organic solvent the unassisted reaction proceeds only over several days and in very poor yield. However, by employing neat acetic acid as both solvent and acid catalyst with microwave irradiation at 160 °C quinoline synthesis is achieved in 5 minutes in excellent yield. This has advantages over the previously reported high temperatures or strong acids required, not least given the green credentials of acetic acid, and examples using diverse ketones illustrate applicability. Additionally, the unassisted reaction proceeds effectively at room temperature, albeit much more slowly.

The Flack Parameter is now almost universally reported for all chiral materials characterized by X-ray crystallography. Its elegant simplicity was an inspired development by Howard Flack, and although the original algorithm for its computation has been strengthened by other workers, it remains an essential outcome for any crystallographic structure determination. As with any one-parameter metric, it needs to be interpreted in the context of its standard uncertainty.

The papain-like protease (PLpro) of SARS-CoV-2 is essential for viral propagation and, additionally, dysregulation of the host innate immune system. Using a library of 40 potential metal-chelating compounds we performed an X-ray crystallographic screening against PLpro. As outcome we identified six compounds binding to the target protein. Here we describe the interaction of one hydrazone (H1) and five thiosemicarbazone (T1-T5) compounds with the two distinct natural substrate binding sites of PLpro for ubiquitin and ISG15. H1 binds to a polar groove at the S1 binding site by forming several hydrogen bonds with PLpro. T1-T5 bind into a deep pocket close to the polyubiquitin and ISG15 binding site S2. Their interactions are mainly mediated by multiple hydrogen bonds and further hydrophobic interactions. In particular compound H1 interferes with natural substrate binding by sterical hindrance and induces conformational changes in protein residues involved in substrate binding, while compounds T1-T5 could have a more indirect effect. Fluorescence based enzyme activity assay and complementary thermal stability analysis reveal only weak inhibition properties in the high micromolar range thereby indicating the need for compound optimization. Nevertheless, the unique binding properties involving strong hydrogen bonding and the various options for structural optimization make the compounds ideal lead structures. In combination with the inexpensive and undemanding synthesis, the reported hydrazone and thiosemicarbazones represent an attractive scaffold for further structure-based development of novel PLpro inhibitors by interrupting protein-protein interactions at the S1 and S2 site.

Summary: Luminescent solar concentrators (LSCs) are simple and cost-effective solar energy-harvesting devices. Indium phosphide (InP)-based colloidal quantum dots (QDs) are promising QDs for efficient LSC devices due to their environmentally benign nature. One major challenge in LSC devices is reabsorption losses. To minimize the reabsorption, Stokes shift engineering is a critical process to designing the QD material. Here, we present a protocol that contains the preparation of structurally engineered copper-doped InP/ZnSe QDs and their LSC application.For complete details on the use and execution of this protocol, please refer to Sadeghi et al. (2020).

Structural investigations of molecular crystal solvates can provide important information for the targeted crystallization of particular inclusion compounds. Here, the crystal structure of the first ether solvate of hexaphenyldistannane [(Ph3Sn)2 • 2 THF] is reported. Structural features in terms of host-guest interactions and in the context of the previously reported polymorphs and solvates of (Ph3Sn)2 are discussed.

Abstract The halogen bond has previously been explored as a versatile tool in crystal engineering and anion coordination chemistry, with mechanochemical synthetic techniques having been shown to provide convenient routes towards cocrystals. In an effort to expand our knowledge on the role of halogen bonding in anion coordination, here we explore a series of cocrystals formed between 3‐iodoethynylpyridine and 3‐iodoethynylbenzoic acid with halide salts. In total, we report the single‐crystal X‐ray structures of six new cocrystals prepared by mechanochemical ball milling, with all structures exhibiting C≡C−I⋅⋅⋅X− (X=Cl, Br) halogen bonds. Whereas cocrystals featuring a pyridine group favoured the formation of discrete entities, cocrystals featuring a benzoic acid group yielded an alternation of halogen and hydrogen bonds. The compounds studied herein were further characterized by 13C and 31P solid‐state nuclear magnetic resonance, with the chemical shifts offering a clear and convenient method of identifying the occurrence of halogen bonding, using the crude product obtained directly from the mechanochemical ball milling. Whereas the 31P chemical shifts were quickly able to identify the occurrence of cocrystallization, 13C solid‐state NMR was diagnostic of both the occurrence of halogen bonding and of hydrogen bonding.

Abstract The emergence of untreatable drug‐resistant strains of Mycobacterium tuberculosis is a major public health problem worldwide, and the identification of new efficient treatments is urgently needed. Mycobacterium tuberculosis cytochrome P450 CYP121A1 is a promising drug target for the treatment of tuberculosis owing to its essential role in mycobacterial growth. Using a rational approach, which includes molecular modelling studies, three series of azole pyrazole derivatives were designed through two synthetic pathways. The synthesized compounds were biologically evaluated for their inhibitory activity towards M. tuberculosis and their protein binding affinity (KD). Series 3 biarylpyrazole imidazole derivatives were the most effective with the isobutyl (10 f) and tert‐butyl (10 g) compounds displaying optimal activity (MIC 1.562 μg/mL, KD 0.22 μM (10 f) and 4.81 μM (10 g)). The spectroscopic data showed that all the synthesised compounds produced a type II red shift of the heme Soret band indicating either direct binding to heme iron or (where less extensive Soret shifts are observed) putative indirect binding via an interstitial water molecule. Evaluation of biological and physicochemical properties identified the following as requirements for activity: LogP >4, H‐bond acceptors/H‐bond donors 4/0, number of rotatable bonds 5–6, molecular volume >340 Å3, topological polar surface area

Thermal rearrangement of the 1,2-bis(silylene), [{(4-ButPh)C(NDip)2}Si−]2 (Dip = 2,6-diisopropylphenyl, leads to the silyl-silylene, {(4-ButPh)C(NDip)2}Si−Si(H) {N(Dip)C(=NDip)(4-ButPh-H)}, via an intramolecular C−H activation reaction. The X-ray crystal structure, and limited spectroscopic data, for the compound are reported. The structure of the silyl-silylene incorporates an exocyclic imine fragment, which is unprecedented for this compound class.

Abstract Background 4-Thiazolidinone ring is reported to have almost all types of biological activities. Also, it present in many marketed drugs. Results Ethyl acetoacetate reacted with phenyl isothiocyanate and ethyl chloroacetate in presence of K2CO3 and DMF to afford the thiazolidinone derivative 5. Thiazolidinone 5 reacted with dimethylformamide-dimethylacetal to afford (Z)-ethyl 2-((Z)-5-((dimethylamino) methylene)-4-oxo-3-phenylthiazolidin-2-ylidene)acetate (6). The structure of thiazolidinone 6 was elucidated from its spectral analysis and X-ray crystallography and was optimized using B3LYP/6-31G(d,p) method. The geometric parameters and NMR spectra were discussed both experimentally and theoretically. Also, the natural charges at the different atomic sites were predicted. The synthesized compounds had moderate cytotoxic activity. Conclusions An unexpected synthesis of (Z)-ethyl 2-((Z)-5-((dimethylamino)methylene)-4-oxo-3-phenylthiazolidin-2-ylidene)acetate via deacetylation mechanism. The structure was established using X-ray and spectral analysis. The geometric parameters, and NMR spectra were discussed. The synthesized compounds showed moderate anticancer activity.

The reaction of copper(II) nitrate and pyridoxal S-methylisothiosemicarbazone (PLITSC) in the presence of ammonium thiocyanate resulted in the formation of two types of complexes. A dimeric complex of the formula [Cu(-PLITSC)NCS2](NCS)2·2MeOH was obtained in the presence of excess of ammonium thiocyanate, while in the presence of its nearly equimolar amount, crystals of a polymeric complex [Cu(-PLITSC)NCS]NO3∙MeOHn were formed. The complexes were characterized by elemental analysis, conductometry, IR spectroscopy, and their structures are unequivocally determined by single crystal X-ray crystallography. In both complexes, the copper atom is five-coordinated, situated in a deformed square-pyramidal environment. The basal plane of the square pyramid is defined by the oxygen atom of the deprotonated phenol group and terminal nitrogen atoms of the isothiosemicarbazide moiety of the Schiff base, as well as the nitrogen atom of the coordinated thiocyanate ion, while the apical site is occupied by the oxygen atom of the hydroxymethyl group of the neighboring asymmetric unit. This coordination mode of the PLITSC was hitherto unknown. A survey of the Cambridge Structural Database showed that the coordination of the hydroxymethyl group is rare within pyridoxal-based Schiff base metal complexes. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172014 and Grant no. III41010]

New polynuclear silver(I) complexes, [Ag(CF3SO3)(4,7-phen)(CH3CN)]n (1) and [Ag(PO2F2)(4,7-phen)]n (2), were synthesized by the reaction of 4,7-phenanthroline (4,7-phen) and the corresponding AgX salt (X = CF3SO3 - and PF6 -) in 1:2 mole ratio, respectively, in methanol/acetone (1:1 volume ratio) at room temperature. The characterization of the complexes was established on the basis of elemental microanalysis, IR and NMR (1H and 13C) spectroscopic techniques, while their crystal structures were determined by single-crystal X-ray diffraction analysis. The results of spectroscopic and crystallographic analyses revealed that in these complexes, 4,7-phen behaves as a bridging ligand between two metal ions, while the remaining coordination sites of the Ag(I) ions are occupied by the oxygen atom of CF3SO3 - and an acetonitrile nitrogen atom in 1 or by two oxygen atoms from two PO2F2 -, formed after hydrolysis of PF6 -, in 2. In the solid state, both complexes are coordination polymers in which the geometry around the Ag(I) ions is distorted tetrahedral. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172036]

The crystal structure of (E)-4-chloro-2-((pyridin-2-ylimino)-methyl)- phenol, recently published by Yıldırım et al. in J. Serb. Chem. Soc. 83 (2018) 707–721, is revised. Refinement of the new structural model against original X-ray diffraction data, deposited with the Cambridge Crystallographic Data Centre, proved that the compound studied by single crystal X-ray diffraction was actually (E)-4-chloro-2-((pyridin-3-ylimino)methyl)phenol.

Abstract Background The synthesis of new thiazole derivatives is very important because of their diverse biological activities. Also , many drugs containing thiazole ring in their skeletons are available in the market such as Abafungin, Acotiamide, Alagebrium, Amiphenazole, Brecanavir, Carumonam, Cefepime, and Cefmatilen. Results Ethyl cyanoacetate reacted with phenylisothiocyanate, chloroacetone, in two different basic mediums to afford the thiazole derivative 6, which reacted with dimethylformamide- dimethyl acetal in the presence of DMF to afford the unexpected thiazole derivative 11. The structures of the thiazoles 6 and 11 were optimized using B3LYP/6-31G(d,p) method. The experimentally and theoretically geometric parameters agreed very well. Also, the natural charges at the different atomic sites were predicted. HOMO and LUMO demands were discussed. The anticancer activity of the prepared compounds was evaluated and showed moderate activity. Conclusions Synthesis of novel thiazole derivatives was done. The structure was established using X-ray and spectral analysis. Optimized molecular structures at the B3LYP/6-31G(d,p) level were investigated. Thiazole derivative 11 has more electropositive S-atom than thiazole 6. The HOMO–LUMO energy gap is lower in the former compared to the latter. The synthesized compounds showed moderate anticancer activity.

This study presents synthesis and characterization of new nano uranyl Schiff base complexes. Electrochemistry of these complexes showed a quasireversible redox reaction without any successive reactions. Furthermore, X-ray crystallography exhibited that beside the coordination of tetradentate Schiff base, one solvent molecule (dimethylformamide) was also coordinated. According to Coats-Redfern plots the kinetics of thermal decomposition of the studied complexes was first-order in all stages. Anticancer activities of the uranyl Schiff base complexes against cancer cell lines (Jurkat) was studied and determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide) assay. The results demonstrated that the complexes with aliphatic bridging units showed less anticancer activities than those having the aromatic units.

Nucleic acid aptamers selected through systematic evolution of ligands by exponential enrichment (SELEX) fold into exquisite globular structures in complex with protein targets with diverse translational applications. Varying the chemistry of nucleotides allows evolution of nonnatural nucleic acids, but the extent to which exotic chemistries can be integrated into a SELEX selection to evolve nonnatural macromolecular binding interfaces is unclear. Here, we report the identification of a cubane-modified aptamer (cubamer) against the malaria biomarker Plasmodium vivax lactate dehydrogenase (PvLDH). The crystal structure of the complex reveals an unprecedented binding mechanism involving a multicubane cluster within a hydrophobic pocket. The binding interaction is further stabilized through hydrogen bonding via cubyl hydrogens, previously unobserved in macromolecular binding interfaces. This binding mechanism allows discriminatory recognition of P. vivax over Plasmodium falciparum lactate dehydrogenase, thereby distinguishing these highly conserved malaria biomarkers for diagnostic applications. Together, our data demonstrate that SELEX can be used to evolve exotic nucleic acids bearing chemical functional groups which enable remarkable binding mechanisms which have never been observed in biology. Extending to other exotic chemistries will open a myriad of possibilities for functional nucleic acids. [ABSTRACT FROM AUTHOR]