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The title chlorin, 2 Ph H 2 , hydrogen-bonded to dimethylaminopyridine (DMAP), C 44 H 32 N 4 O 2 ·C 7 H 10 N 2 , and its corresponding zinc(II) complex, 2 Ph Zn , axially coordinated to ethylenediamine (EDA), [Zn(C 44 H 30 N 4 O 2 )]·C 2 H 8 N 2 , were isolated and crystallized by adventitious reduction of the corresponding osmate esters by DMAP and EDA, respectively. Known since 1996 and, inter alia , used for the preparation of a wide range of (planar and non-planar) chlorin analogues (so-called pyrrole-modified porphyrins), their conformational analyses in the solid state are important benchmarks. Both macrocycles are only modestly distorted from planarity and both are slightly more non-planar than the corresponding dimethoxy-derivative, but less planar than a free-base meso -pentafluorophenyl-based osmate ester. NSD analyses provide quantitative and qualitative analyses of the distortion modes. One origin of the non-planarity is presumably the avoidance of the eclipsed configuration of the two vic–cis diols on the pyrroline moiety; the resulting deformation of the pyrroline translates in some cases into the macrocycle. The structure of 2 Ph H 2 features voids making up ca 26% of the unit-cell volume filled with highly disordered solvate molecules (chloroform and hexanes). 2 Ph Zn crystallized with a 13.6 (4)% occupied solvate methanol molecule. 

Bis(benzene-1,2-diolato-κ 2 O , O ′)bis(dimethyl sulfoxide-κ O )titanium(IV), [Ti(C 6 H 4 O 2 ) 2 (C 2 H 6 OS) 2 ], crystallizes with two crystallographically independent molecules in the space group P 2 1 / c emulating orthorhombic Pbca symmetry (β = 90.0445 (9)°]. The two molecules are related by pseudo-glide symmetry, broken by modulation of each one catecholate and dimethyl sulfoxide (DMSO) ligand. Twinning by pseudomerohedry was observed [twin ratio 0.5499 (7):0.4401 (7)]. Complex 3 was obtained by heating of diprotonated titanium tris-catecholate precursor 2 H in DMSO, by formal displacement of a catechol molecule by two DMSO molecules. Complex 3 is just the second heteroleptic, mono-nuclear, neutral bis-catecholate complex with TiO 6 metal coordination, the only other one being its bis-DMF analogue 6 . The two molecules of 3 exhibit a distorted octahedral geometry. The geometry and distortions from ideal symmetry of 3 are discussed and compared to 6 and to cationic tris-catecholate titanium complexes. 

The translation of the solution phase, base-induced formation of a chromene-annulated chlorin from the corresponding meso-tetrakis(pentafluorophenyl)-2,3-dihydroxychlorin using a mechanochemical approach (ball milling) is possible, but fraught with unexpectedly large difficulties associated with the grinding aids used. 

Ion selective electrode (ISE) sensors have been broadly applied for real-time in situ monitoring of ion concentrations in water environments. However, ISE sensors suffer from critical problems, such as ionophore leaching, water-penetration, poor electrochemical stability, and resulting short life spans. In this study, a template-guided membrane matrix immobilization strategy was pursued as a novel ISE sensor fabrication methodology to enhance its sensing characteristics and longevity. Specifically, nano-porous anodized aluminum oxide (AAO) was used as the template for an NH 4 + -specific ISE sensor. A nano-porous nickel mesh eventually replaced the template and formed a compact, high-surface juncture with the NH 4 + ion-selective membrane matrix. The resulting template-guided nano-mesh ISE (TN-ISE) sensor displayed enhanced electrochemical stability ( i.e. , capacitance increased by 50%, reading drift reduced by 75%) when compared to a regular single-wall carbon nanotube (SW-CNT) ISE sensor used as the standard. The interface between the nano-mesh electrode and the ion selective membrane matrix was compact enough to prevent water influx at the electrode interface. This minimized ionophore leaching and increased the mechanical integrity of the TN-ISE sensor. The practical advantages of the novel sensor were validated via long-term (360 hours) tests in real wastewater, returning a small average error of 1.28% over this time. The results demonstrate the feasibility of the template-guided nano-mesh design and fabrication strategy toward ISEs for long-term continuous monitoring of water or wastewater quality. 

Octaethyltrioxopyrrocorphins unexpectedly show macrocycle-aromatic properties, even though they contain the macrocyclic π-system of the non-aromatic pyrrocorphins (hexahydroporphyrins). Two of the four possible triketone regioisomers were first reported in 1969 by one-pot oxidation of octaethylporphyrin but remained essentially unexplored since. We detail here the targeted preparation of the remaining two triketone isomers and the optical and NMR spectroscopic properties of all isomers. All four regioisomers possess unique electronic properties, including broadly varying degrees of diatropicity that were experimentally determined using 1 H NMR spectroscopy and computationally verified. Structural patterns modulating the aromaticity were recognized. These differences highlight the regioisomerically differentiated influences of the three β-oxo-functionalities. We also present the solid state structure of the two most common isomers (in their free base form or as zinc complexes), allowing further conclusions to be made about the resonance structures present in these triketones. Remarkably, also, the halochromic properties of the triketones differ sharply from those of regular (hydro)porphyrins, providing further support for the proposed 16-membered, 18 π-electron aromatic ring-current. The work conceptually expands the understanding of tris-modified hydroporphyrinoid analogues and the factors that enable and control porphyrinoid aromaticity.