The enrichment ratio of atomic contacts in the crystal structure of isomeric, triply protonated, 4′-functionalized terpyridine cations with [ZnCl4]2− as counter-ion

We report herein the synthesis, crystallographic analysis and a study of the non-covalent interactions observed in the new 4′-substituted terpyridine-based derivative bis[4′-(isoquinolin-2-ium-4-yl)-4,2′:6′,4′′-terpyridine-1,1′′-diium] tris-[tetrachloridozincate(II)], (C24H19N4)2[ZnCl4]3 or (44TPH3)2[ZnCl4]3, where (44TPH3)3+ is the triply protonated cation 4′-(isoquinolinium-4-yl)-4,2′:6′,4′′ terpyridinium. The compound is similar in its formulation to the recently reported 2,2′:6′,2′′ terpyridinium analogue {bis[4′-(isoquinolin-2-ium-4-yl)-2,2′:6′,2′′-terpyridine-1,1′′-diium] tris[tetrachloridozincate(II)] monohydrate; Granifo et al. (2017). Acta Cryst. C73, 1121–1130}, although rather different and much simpler in its structural features, mainly in the number and type of non-covalent interactions present, as well as in the supramolecular structure they define.

Crystallographic and computational study of a network composed of [ZnCl4]2− anions and triply protonated 4′-functionalized terpyridine cations

We report herein the synthesis, crystallographic analysis and a study of the noncovalent interactions observed in the new 4′-substituted terpyridine-based derivative bis[4′-(isoquinolin-2-ium-4-yl)-2,2′:6′,2′′-terpyridine-1,1′′-diium] tris[tetrachloridozincate(II)] monohydrate, (C24H19N4)2[ZnCl4]3·H2O or (ITPH3)2[ZnCl4]3·H2O, where (ITPH3)3+ is the triply protonated cation derived from 4′-(isoquinolin-4-yl)-2,2′:6′,2′′-terpyridine (ITP) [Granifo et al. (2016). Acta Cryst. C72, 932–938]. The (ITPH3)3+ cation presents a number of interesting similarities and differences compared with its neutral ITP relative, mainly in the role fulfilled in the packing arrangement by the profuse set of D—H...A [D (donor) = C, N or O; A (acceptor) = O or Cl], π–π and anion...π noncovalent interactions present. We discuss these interactions in two different complementary ways, viz. using a point-to-point approach in the light of Bader's theory of Atoms In Molecules (AIM), analyzing the individual significance of each interaction, and in a more `global' analysis, making use of the Hirshfeld surfaces and the associated enrichment ratio (ER) approach, evaluating the surprisingly large co-operative effect of the superabundant weaker contacts.

Reactions and interactions between peri-groups in 1-dimethylamino-naphthalene salts: an example of a “through space” amide

Abstract8-Dimethylaminonaphthalene-1-carbaldehyde reacts readily at 0°C with benzoyl or pivaloyl chloride by O-acylation and formation of a N–C bond (1.566(2)–1.568(3) Å) between the peri-substituents to give a salt. The reaction is promoted by electron donation from the dimethylamino group to the carbonyl group, akin to the properties of an amide. In contrast, the corresponding methyl ester and N,N-diisopropylamide react with acid in ether by protonation of the dimethylamino group and formation of a hydrogen bond to the carbonyl group, while under similar conditions the N,N-dimethylamide undergoes ready hydrolysis to the acid. The structures of products are determined by X-ray crystallography, and from the latter hydrolysis crystals containing zwitterionic 1-dimethylammonium-naphthalene-8-carboxylate and the corresponding O-protonated cation along with dimethylammonium and triflate ions were obtained.

Two New Chromium(III) Complexes with the Pincer-type Pyridine-2,6-dicarboxylate Ligand

The synthesis and crystal structures of two new salts of chromium(III) with pyridine-2,6-dicarboxylic acid H2Pda (and 2,2’-bipyridyl, Bpy, as a co-ligand) are reported, (HPyz)[Cr(Pda)2](H2Pda)-(H2O)5 (1) and [Cr(Pda)(Bpy)(H2O)][Cr(Pda)2](H2O)2 (2). Both crystal structures contain the octahedral [Cr(Pda)2]− anion with the pincer-type O,N,O-Pda2− ligand. In 1, the pyrazole additive does not act as a ligand, rather it is included as a mono-protonated cation. In 2, both Pda2−, the neutral 2,2’-bipyridyl and water are coordinating Cr3+ in the cation [Cr(Pda)(Bpy)(H2O)]+.

Proton Conduction in Solids: Bulk and Interfaces

Truly proton-conducting materials would have an immense impact on sustainable energy technologies for the 21st century, through efficient fuel cells, electrolyzers, and gas-separation membranes. However, proton conduction combined with materials stability seems difficult to achieve, and some hurdles and pathways are outlined in this article. Problems, possibilities, and artifacts of transport across and along interfaces are discussed, linked mainly to space-charge layer properties and engineering of the grain-boundary core and to water in nanovoids. The importance of protons in many semiconducting functional oxides is also explained. At lower temperatures and in humid environments, the presence of protonated cation vacancies (Ruetschi defects) is predicted and is expected to play an important role in photoelectrochemistry, catalysis, and surface transport.