Described herein an alternative synthetic approach for conjugated indeno[2,1-c]fluorene, including the experimental and theoretical investigations of a tetraradicaloid s-indaceno[2,1-c:6,5-c']difluorene that belongs to the rarely explored indacenodifluorene family containing 4n+2 monocyclic...

Parent 2,3:10,11-dibenzoheptazethrene is a singlet diradicaloid polycyclic hydrocarbon in the ground state that did not change its diradical character upon substitution (methyl and triisopropylsilylethynyl). Described herein are the synthesis and characterization of an ethoxy/3,5-(CF3)2C6H3-substituted 2,3:10,11-dibenzoheptazethrene 3 that prefers to retain its p-quinoidal core and shows zero diradical character, as determined by single-crystal analysis and density functional theory calculations. Negative solvatochromism, π–π interactions, Csp2 –H···O hydrogen bonding, intramolecular charge transfer, redox amphotericity, and a narrow HOMO–LUMO energy gap make 3 a potential candidate for application in optoelectronics.

Dicyclopenta[c]fluorenothiophene 5 was synthesized as the isoelectronic polycyclic heteroarene analogue of an as-indacenodifluorene with a (4n + 2)π-electron perimeter. Single-crystal and 1 H NMR analyses indicated a quinoidal ground state for 5, which was supported by theoretical calculations while suggesting a degree of antiaromaticity of the as-indacene subunit greater than that for sindacenodifluorene 3. The dominant antiaromaticity for 5 was evidenced by the broad weakly intense absorption tail reaching the near-IR region, four-stage redox amphotericity, and small HOMO− LUMO energy gap.

Molecular interactions of amino acids with ionic liquids are significant to study the molecular stability and physicochemical properties of amino acids. Mixtures of amino acids l-leucine and N-acetyl-l-leucine + (0.005, 0.010, 0.030, and 0.050 mol·kg–1) aqueous solution of ionic liquid (1-butyl-3-methylimidazolium chloride) at temperature T = (288.15, 298.15, 308.15, and 318.15 K) have been studied by density and speeds of sound measurements. Volumetric properties have been obtained by utilizing data of density. Volumetric properties include apparent molar volumes, partial molar volumes at infinite dilution, limiting partial molar volumes of transfer at infinite dilution, apparent molar expansibility, etc. Similarly, speeds of sound measurements are utilized to calculate corresponding parameters like apparent molar isentropic compression, K ϕ,s, apparent molar isentropic compression at infinite dilution, K ϕ,s 0, and transfer compressibility at infinite dilution ΔK ϕ,s 0. Results confirmed the predominance of the hydrophilic–hydrophilic interaction over the hydrophobic–hydrophobic interaction in ternary solutions.

peri-Acenoacenes are attractive synthetic targets, but their nonbenzenoid isomeric counterparts were unnoticed. 1-Ethoxyphenanthro[9,10e]acephenanthrylene 8 was synthesized and converted to azulene-embedded 9, which is a tribenzo-fused non-alternant isomeric motif of peri-anthracenoanthracene. Aromaticity and single-crystal analyses suggested a formal azulene core for 9, which showed a smaller highest occupied molecular orbital (HOMO)−lowest unoccupied molecular orbital (LUMO) energy gap with a charge-transfer absorption band and brighter fluorescence than 8 (quantum yield (Φ): 9 = 41.8%, 8 = 8.9%). The reduction potentials of 8 and 9 were nearly identical, and the observations were further supported by density functional theory (DFT) calculations.