Joel Bernstein (1941-2019).

Joel Bernstein, former Barry and Carol Kaye Professor of Applied Science at Ben-Gurion University, passed away on January 2, 2019. His legacy to the scientific community is a body of work on organic solid-state chemistry, chemical crystallography, polymorphism, hydrogen bonding, graph sets, structure-property relations, organic conducting materials, and pharmaceuticals.

Kinetics of solid state photodimerization of 1,4-dimethyl-2-pyridinone in its molecular compound.

The [4 + 4] photodimerization of 1,4-dimethyl-2-pyridinone (A) in its molecular compound with 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol (I) was investigated by irradiation of a single crystal of the compound. The conversion to the product in a single-crystal to single-crystal transformation enabled the determination of its crystal structure after each exposure cycle of 10-20 min with a pulsed 355 nm laser light. The unit cell changes as a function of the conversion were monitored and showed monotonic changes.

Structural comparisons between methylated and unmethylated nitrophenyl lophines.

The lophine derivative 2-(2-nitrophenyl)-4,5-diphenyl-1H-imidazole, C21H15N3O2, (I), crystallized from ethanol as a solvent-free crystal and from acetonitrile as the monosolvate, C21H15N3O2.C2H3N, (II). Crystallization of 2-(4-nitrophenyl)-4,5-diphenyl-1H-imidazole from methanol yielded the methanol monosolvate, C21H15N3O2.

Structural effects on the solid-state photodimerization of 2-pyridone derivatives in inclusion compounds.

The structures of six crystalline inclusion compounds between various host molecules and three guest molecules based on the 2-pyridone skeleton are described. The six compounds are 1,1'-biphenyl-2,2'-dicarboxylic acid-2-pyridone (1/2), C(14)H(10)O(4).2C(5)H(5)NO, (I-a), 1,1'-biphenyl-2,2'-dicarboxylic acid-4-methyl-2-pyridone (1/2), C(14)H(10)O(4).