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The steric interference of proximal dialkyl amino and acyl groups at the peri (1,8) positions of naphthalene affects the intramolecular charge transfer fluorescence. Previous studies indicate that acyl and freely rotating dimethyl amino groups twist toward coplanarity with the naphthalene ring in the excited state. The present study examines the effect of constraining the amino group in a ring. The photophysical properties of 2,2-dimethyl-1-(1-methyl-1,2,3,4-tetrahydrobenzo[h]quinolin-10-yl)propan-1-one (4), ethyl 1-methyl-1,2,3,4-tetrahydrobenzo[h]quinoline-10-carboxylate (5), and 1-methyl-1,2,3,4-tetrahydrobenzo[h]quinoline-10-carbaldehyde (6) are compared with the dimethyl amino derivatives 2 and 3. Crystal structures of 4-6 show that the amine ring adopts a chair conformation, where the N-methyl group is axial. Computational results suggest that the pyramidal amino group planarizes and twists together with the acyl toward coplanarity in the excited state. The ring structure does not thwart the formation of a planar intramolecular charge transfer (PICT) state. [ABSTRACT FROM AUTHOR]

The preparation of single crystals of sparingly soluble polycyclic aromatic compounds in MeCN is facilitated by solubilizing ionic host–guest complexation under otherwise poor solvent conditions. The guest is then crystallized within minutes through controlled guest displacement from the host via competitor equilibria, or over days through direct crystallization of the host–guest complex itself. [ABSTRACT FROM AUTHOR]

The macrometallacyclic title compound, [Hg4Br4(C8H11N2S)4] or [((HgL2)(HgBr2))2] (1) where HL = 2-{[(pyridin-2-yl)methyl]amino}ethane-1-thiol, was prepared and structurally characterized. The Hg2+ complex crystallizes in the P21/c space group. The centrosymmetric Hg4S4 metallacycle is constructed from metal ions with alternating distorted tetrahedral Br2S2 and distorted seesaw N2S2 primary coordination environments with pendant pyridyl groups. The backfolded extended chair metallacycle conformation suggests interactions between each of the bis-chelated mercury atoms and Br atoms lying above and below the central Hg2S4 plane. Supramolecular interactions in 1 include a fourfold aryl embrace and potential hydrogen bonds with bromine as the acceptor. Hirshfeld surface analysis indicates that H• • •H (51.7%), Br• • •H/ H• • •Br (23.0%) and C• • •H/H• • •C (9.5%) interactions are dominant. [ABSTRACT FROM AUTHOR]

Crystals of the title salt, (C 8 H 20 N)[Sn(C 6 H 5 ) 3 (C 2 H 2 O 2 S)], comprise diisobutyl-ammonium cations and mercapto-acetato-tri-phenyl-stannate(IV) anions. The bidentate binding mode of the mercapto-acetate ligand gives rise to a five-coordinated, ionic tri-phenyl-tin complex with a distorted cis -trigonal-bipyramidal geometry around the tin atom. In the crystal, charge-assisted ammonium-N-H⋯O(carboxyl-ate) hydrogen-bonding connects two cations and two anions into a four-ion aggregate. Two positions were resolved for one of the phenyl rings with the major component having a site occupancy factor of 0.60 (3)., (© Song et al. 2024.)

Reactions of BiI 3 /CuI mixtures with tetrahydrothiophene (THT) in toluene produce 2-D sheet networks BiCu 3 I 6 (THT) n ( n = 2, 3, or 4), depending on reaction conditions. All three structures are based on BiI 6 octahedra, which share pairs of (μ 2 -I) 2 with Cu 3 (THT) n units. BiCu 3 I 6 (THT) 2 features Cu 2 (μ 2 -I) 2 rhombs with close Cu···Cu interactions and is accompanied by formation of the very complex HBi 3 Cu 12 I 22 (THT) 8 . Reactions of SbI 3 /CuI with THT in toluene produced a SbCu 3 I 6 (THT) 2 network shows Cu 3 (μ 2 -THT) 2 units, like its Bi congener, but Cu 6 (μ 2 -I) 6 barrels rather than rhombs. Isolated SbI 3 units are stacked above the Cu 6 I 6 barrels. A molecular compound, Sb 3 Cu 3 I 12 (THT) 6 consists of a face-sharing Sb 3 I 12 stack, in which the Cu-THT units are bonded in asymmetric fashion about the central SbI 6 . Metal-halide bonds were investigated via QTAIM and NLMO analyses, demonstrating that these bonds are largely ionic and occur between the Bi/Sb and I p orbitals. Hirshfeld analysis shows significant H···H and H···I interactions. Diffuse reflectance spectroscopy (DRS) reveals band edges for the Bi species of 1.71-1.82 eV, while those for the neutral Sb complexes are in the range of 1.94-2.06 eV. Mapping of the electronic structure via density of state calculations indicates population of antibonding Bi/Sb-I orbitals in the excited state.

The activation of the CP/LP C3 proconvertase complex is a key event in complement activation and involves cleavage of C4 and C2 by the C1s protease (classical pathway) or the mannose-binding lectin-associated serine protease (MASP)-2 (lectin pathway). Efficient cleavage of C4 by C1s and MASP-2 involves exosites on the complement control protein and serine protease (SP) domains of the proteases. The complement control protein domain exosite is not involved in cleavage of C2 by the proteases, but the role of an anion-binding exosite (ABE) on the SP domains of the proteases has (to our knowledge) never been investigated. In this study, we have shown that the ABE on the SP of both C1s and MASP-2 is crucial for efficient cleavage of C2, with mutant forms of the proteases greatly impaired in their rate of cleavage of C2. We have additionally shown that the site of binding for the ABE of the proteases is very likely to be located on the von Willebrand factor domain of C2, with the precise area differing between the enzymes: whereas C1s requires two anionic clusters on the von Willebrand factor domain to enact efficient cleavage of C2, MASP-2 apparently only requires one. These data provide (to our knowledge) new information about the molecular determinants for efficient activation of C2 by C1s and MASP-2. The enhanced view of the molecular events underlying the early stages of complement activation provides further possible intervention points for control of this activation that is involved in a number of inflammatory diseases., (Copyright © 2024 by The American Association of Immunologists, Inc.)

The macrometallacyclic title compound, [Hg 4 Br 4 (C 8 H 11 N 2 S) 4 ] or [((Hg L 2 )(HgBr 2 )) 2 ] ( 1 ) where HL = 2-{[(pyridin-2-yl)meth-yl]amino}-ethane-1-thiol, was prepared and structurally characterized. The Hg 2+ complex crystallizes in the P 2 1 / c space group. The centrosymmetric Hg 4 S 4 metallacycle is constructed from metal ions with alternating distorted tetra-hedral Br 2 S 2 and distorted seesaw N 2 S 2 primary coordination environments with pendant pyridyl groups. The backfolded extended chair metallacycle conformation suggests inter-actions between each of the bis-chelated mercury atoms and Br atoms lying above and below the central Hg 2 S 4 plane. Supra-molecular inter-actions in 1 include a fourfold aryl embrace and potential hydrogen bonds with bromine as the acceptor. Hirshfeld surface analysis indicates that H⋯H (51.7%), Br⋯H/H⋯Br (23.0%) and C⋯H/H⋯C (9.5%) inter-actions are dominant., (© Thomas et al. 2023.)

Metallothioneins (MTs) are a ubiquitous class of small cysteine-rich metal-binding proteins involved in metal homeostasis and detoxification with highly versatile metal binding properties. Despite the long-standing association of MT with M 3 S 3 and M 4 S 5 metal clusters, synthetic complexes with these core architectures are exceptionally rare. Here, we demonstrate an approach to synthesizing and characterizing aggregates of group 12 metal ions with monocyclic M 3 S 3 cores in acetonitrile solution without the protection of a protein. Multidentate monothiol ligand N , N -bis(2-pyridylmethyl)-2-aminoethanethiol ( L1H ) provided [Cd 3 ( L1 ) 3 ](ClO 4 ) 3 ( 1 ), the first structurally characterized nonproteinaceous aggregate with a metallothionein-like monocyclic Cd 3 S 3 core. In addition, [Zn 3 ( L1 ) 3 ](ClO 4 ) 3 ·4CH 3 CN ( 2 ·4CH 3 CN) was characterized by X-ray crystallography. The complex cations of 1 and 2 had comparable structures despite being nonisomorphic. Variable temperature and concentration 1 H NMR were used to investigate aggregation equilibria of 1 , 2 , and a precipitate with composition "Hg( L1 )(ClO 4 )" ( 3 ). Cryogenic 1 H NMR studies of 3 revealed a J ( 199 Hg 1 H) coupling constant pattern consistent with an aggregate possessing a cyclic core. ESI-MS was used for gas-phase characterization of 1 - 3 , as well as mixed-metal [M 2 M'( L1 ) 3 (ClO 4 ) 2 ] + ions prepared in situ by pairwise acetonitrile solution combinations of the group 12 complexes of L1 . Access to synthetic variants of metallothionein-like group 12 aggregates provides an additional approach to understanding their behavior.