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Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296

July 2019 issue

Highlighted illustration

Cover illustration: An intuitive method is presented for detecting pseudosymmetries in Z' > 1 cases as a complement to well-proven strategies already available in the literature. It is based in the simple idea that the mid-points between equivalent atoms in symmetrically related mol­ecules are disposed according to simple well-known patterns, which are easily recognizable by optical inspection. A number of Z' = 4 cases in the literature are analyzed, which allows some of the potentialities of the method to be revealed. See Baggio [Acta Cryst. (2019), C75, 837-850].

scientific commentaries


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Polymorphs often have different values of Z′, the number of independent molecules in the asymmetric unit of the crystal structure. Structures with Z′ > 1 are a small minority, particularly so for Z′ > 2, and many are associated with packing problems, disorder and weak intermolecular interactions. These phenomena are fascinating and have important practical implications.

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A new method for identifying and visualizing approximate symmetry in mol­ecular crystals is discussed.

feature articles


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An intuitive method is presented for detecting pseudosymmetries in Z′ > 1 cases as a complement to well-proven strategies already available in the literature. It is based on the simple idea that the mid-points between equivalent atoms in symmetrically related mol­ecules are disposed according to simple well-known patterns, which are easily recognizable by optical inspection.

research papers


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There are four independent mol­ecules in the P\overline{1} asymmetric unit of cloxazolam, related by a striking pseudosymmetry. The identical mol­ecules consist of four rings linked in a rather rigid fashion. Even in the absence of strong hydrogen-bond inter­actions, the structure presents an unusual compactness (Kitaigorodskii packing index ≃ 0.71).

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The luminescence quenching of two ZnII MOFs with mixed 5-amino-2,4,6-tri­bromo­isophthalic acid and bipyridyl-type ligands by NAEs have been investigated.

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The monovanadium-substituted β-octa­molybdate [VMo7O26]5− was prepared by a one-pot approach using peroxido complexes of vanadium. 51V NMR spectroscopy confirmed the high selectivity of the synthesis.

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A new nickel(II) cluster-based coordination polymer featuring high-nuclearity nickel(II) secondary building units was successfully prepared, and a tightly packed nanocomposite with extra-long cycling stability (>5000 cycles) was formed by sinter­ing the coordination precursor. This structure and composite have rarely been investigated in significant detail.

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A new phosphate, K3Eu5(PO4)6, with a three-dimensional open framework of [Eu5(PO4)6], is reported. Under near-UV light excitation, it shows a strong red emission due to the characteristic 4f→4f transition of the Eu3+ ion.

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The crystal structures of Group 12 complexes and their precursor, 4-phenyl-5-(pyridin-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione, were studied. The role of hydrogen bonding and other weak interactions in crystal packing was analyzed.

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A monoclinic polymorph of αβ-D-lactose has been identified from crystalline phase mixtures obtained by oven drying concentrated aqueous solutions of D-lactose. This is the second crystalline form of αβ-D-lactose to be identified and it has a high degree of structural three-dimensional similarity to the previously identified triclinic form.

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The first silver bis­muth borate, AgBi2B5O11, has been prepared via glass crystallization. Its acentric structure is derived from that of centrosymmetric Bi3B5O12 by ordered substitution of one Ag+ ion for Bi3+.

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The crystal structure of 4,4′-(cyclo­hexane-1,1-di­yl)bis­[N,N-bis­(4-meth­oxy­phen­yl)aniline] was determined and its photophysical and electrochemical properties investigated. It is expected that the compound will be a good candidate for a hole-transporting material in electronic devices.

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Mononuclear [Ni(L)2] and dinuclear [Cu(L)(μ1,1-N3)]2 types of complexes were obtained from N,N′,O-donor acyl­hydrazone ligand HL. The two complexes show potent urease inhibitory activity and suitable binding affinity to BSA.

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The X-ray structures of CdII–croconate versus PbII–croconate coordination polymers present one-dimensional coordination patterns with a planar configuration for CdII and a nonplanar hemidirected geometry for PbII.

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The mol­ecular structure of a PEPPSI precatalyst, as well as general remarks about PEPPSI complexes compared to NHC complexes, is presented using quantum chemical computations and CSD searches highlighting the importance of π-back-donation in PEPPSI complexes.

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The reaction between 2-[2-(amino­eth­yl)amino]­ethanol and pyridine-2-carbaldehyde in a 1:2 molar ratio affords a mixture containing 2-({2-[(pyridin-2-yl­methyl­idene)amino]­eth­yl}amino)­ethanol (PMAE) and 2-[2-(pyridin-2-yl)oxazolidin-3-yl]-N-(pyridin-2-yl­methyl­idene)ethanamine (POPME). Treatment of this mixture with copper(II) chloride or cadmium(II) chloride gave [Cu(HPMAE)Cl3]·H2O, 1, and [CdCl2(POPME)], 2. The ability of PMAE, POPME and 1 to inter­act with ten selected biomolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II and B-DNA) was investigated by docking studies and compared with doxorubicin.

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Two (3,8)-coordinated three-dimensional networks based on a tetra­nuclear hy­droxide cobalt(II) cluster or with a tetra­nuclear hy­droxide copper(II) cluster, 1,3-bis­[(1,2,4-triazol-4-yl)meth­yl]benzene and benzene-1,3,5-tri­carboxyl­ate were synthesized. The compounds exhibit good photocatalytic degradation of the organic dyes methyl­ene blue (MB) and rhodamine B (RhB) under visible-light irradiation.

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ZnO-Co3O4 nanocomposites embedded in N-doped carbon (ZnO-Co3O4@N-C) nanocages with hollow dodeca­hedral shapes were successfully prepared by the simple carbonizing and oxidizing of metal–organic frameworks (MOFs). Benefiting from the advantages of structural features, the as-prepared ZnO-Co3O4@N-C nanocages display enhanced electrochemical performance when employed as anode materials for Li-ions batteries, which show a discharge capacity of 2373 mAh g−1 for the first cycle and exhibit a retention capacity of 1305 mAh g−1 even after 300 cycles at 0.1 A g−1.

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A zinc(II) com­pound, prepared by the reaction of Zn(NO3)2·6H2O with 4,4′-sulfonyldi­benzoic acid and 4,4′-bis­(2-methyl­imidazol-1-yl)diphenyl ether in H2O, possesses a threefold inter­penetrating two-dimensional 44-sql network and exhibits a highly selective and sensitive sensing for Fe3+ ions in aqueous solution.

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A novel AuI/AgI tetra­nuclear formamidinate complex consisting of a disordered potential derived from six unique metal complexes is reported. DFT calculations were performed to investigate the optimized structures of the individual unique metal complexes and the electronic and luminescence properties of the structure.

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A new coordination polymer formulated as [Co(3,4′-obb)(4,4′-bipy)]n (3,4′-obb2− is 3,4′-oxydibenzoate and 4,4′-bipy is 4,4′-bi­pyridine) was prepared by the self-assembly of Co(NO3)2·6H2O with the rarely used 3,4′-obbH2 ligand and 4,4′-bipy under solvothermal conditions, and has been structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography and powder X-ray diffraction.

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A simple and straightforward synthesis of a heteroscorpionate tungsten complex has been developed. The crystal structures of the tungsten complex and the heteroscorpionate mol­ecule have been analysed. he Hirshfeld surface analysis shows a change of the inter­molecular contacts due to the coordination of the WO2Cl unit with the ligand mol­ecule.

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Two isostructural CdII/ZnII coordination polymers containing a flexible tripodal ligand were synthesized and characterized. The anti­oxidant activities against DPPH and the anti­diabetic activities against α-amylase were evaluated in vitro.

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The silver(I) complex of 2-(4-nitro­benzene­sulfonamido)­benzoic acid (HL) was analyzed by IR and NMR spectroscopies, and single-crystal X-ray crystallography. The Ag⋯Ag inter­action shows an OOOCAg⋯AgOOOC environment in the polymeric complex. The human serum albumin (HSA) inter­actions were analyzed by stead-state fluorescence, where the complex AgL–HSA presented an inter­action 20-times stronger compared to the HL–HSA inter­action.

Special and virtual issues

Acta Crystallographica Section C has recently published special issues on

NMR Crystallography (March 2017)

Scorpionates: a golden anniversary (November 2016)

Full details are available on the special issues page.

The latest virtual issue features Coordination polymers, with an introduction by Len Barbour.

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