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This investigation demonstrates that a series of biphenylenes can be easily prepared from their corresponding halobiphenyls by the cyclization of in situ generated 2′,3′-didehydro-2-lithiobiphenyls at low temperature. Two remarkable advantages of this synthetic method include 1) the lack of any need for transition-metal catalysts or reagents in the cyclization, and 2) the ability to obtain C1-functionalized products by treating the reaction intermediate 1-lithiobiphenylene with an electrophilic reagent. π-Extended derivatives, such as benzobiphenylenes, dibenzobiphenylene, linear/angular [3]phenylenes, and biphenyleno[2,3- b]biphenylenes, were synthesized similarly using suitable biaryls or teraryls. [ABSTRACT FROM AUTHOR]

The association behavior of an electron-donating, bowl-shaped, truxene-based tetrathiafulvalene (truxTTF) with two corannulene-based fullerene fragments, C32H12 and C38H14, is investigated in several solvents. Formation of 1:1 complexes is followed by absorption titrations and complemented by density functional theory (DFT) calculations. The binding constants are in the range log Ka=2.9-3.5. DFT calculations reveal that the most stable arrangement is the conformation in which the 1,3-dithiole ring of truxTTF is placed inside the concave cavity of the corannulene derivative. This arrangement is confirmed experimentally by NMR measurements, and implies that a combination of π-π and CH-π interactions is the driving force for association. Time-dependent DFT calculations reproduce the experimental UV/Vis titrations and provide a detailed understanding of the spectral changes observed. Femtosecond transient absorption studies reveal the processes occurring after photoexcitation of either C32H12 or C38H14 and their supramolecular associates with truxTTF. In the case of truxTTF⋅C38H14, photoexcitation yields the charge-separated state truxTTF.+⋅C38H14.− with a lifetime of approximately 160 ps. [ABSTRACT FROM AUTHOR]

The sulfonated graphene oxide (GO-OSO 3 H) was synthesized by the oxidation of GO under concentrated H 2 SO 4 conditions. It is demonstrated based on characterization results that sulfonated groups was satisfactorily grafted on the surface of GO. Macroscopic investigation indicated that the adsorption of Eu(III) on GO-OSO 3 H can be better fitted by pseudo-second-order kinetic model with high correlation coefficient (R 2 > 0.999) compared to pseudo-first-order kinetic model (R 2 < 0.95). The adsorption of Eu(III) on GO-OSO 3 H was independent of ionic strength, revealing that inner-sphere surface complexation dominated the Eu(III) adsorption at pH from 2.0 to 11.0. The maximum adsorption capacity of GO-OSO 3 H for Eu(III) calculated from Langmuir model was 125.0 mg/g at pH 5.5 and T = 293 K conditions. The calculation of thermodynamic parameters showed that the adsorption of Eu(III) on GO-OSO 3 H was an exothermal and spontaneous processes. According to fitting of surface complexation modeling, the adsorption of Eu(III) on GO-OSO 3 H can be satisfactorily simulated by diffuse layer model with monodentate and mononuclear complexes (SOEu 2 + species) and bidentate and mononuclear complexes ((SO) 2 Eu (OH) 3 − species) at pH 2.0–11.0 conditions. [ABSTRACT FROM AUTHOR]

The palladium-catalyzed annulation of 9-bromo- and 9-chlorophenanthrenes with alkynes gave 4,5-disubstituted acephenanthrylenes in yields of 58-95 % (9 examples). Asymmetric alkynes, such as 1-phenyl-1-propyne, 1-phenyl-1-hexyne, and 1-cyclopropyl-2-phenylethyne, regioselectively form (cyclo)alkyl-substituted products, following the regular rule that governs the carbopalladation of alkynes. This synthetic protocol can also be utilized in annulations with several π-extended bromoarenes, such as 7-bromo[5]helicene, 5-bromo[4]helicene, 9-bromoanthracene, 3-bromoperylene, and 3-bromofluoranthene, to give the corresponding annulated products in moderate to good yields (51-86 %; 6 examples). Similarly, bromocorannulene produced highly curved 1,2-disubstituted cyclopentacorannulenes. Reactions of 6,12-dibromochrysene and 4,7-dibromo[4]helicene with di(4-tolyl)ethyne provided the twofold annulated products in moderate yields. 4,5-Diphenylacephenanthrylene and 6,7-diphenylbenzo[ a]acephenanthrylene thus generated were converted into phenanthro[9,10- e]acephenanthrylene and benzo[ a]phenanthro[9,10- e]acephenanthrylene, respectively, by oxidative cyclodehydrogenation. The structures of 4,5-diphenylacephenanthrylene, 4,5-diphenyldibenzo[ a, l]acephenanthrylene, 1,2-diarylcyclopentacorannulenes, and benzo[ a]phenanthro[9,10- e]acephenanthrylene were verified by X-ray crystallography. The photophysical and electrochemical properties of the selected annulated products were investigated. [ABSTRACT FROM AUTHOR]

The syntheses, structures, and physical properties of dibenzozethrenes were explored. The results thus obtained were compared with those for zethrenes. Dibenzozethrenes were synthesized by the nickel-catalyzed cyclodimerization of 9-ethynyl-1-iodoanthracenes. The substituents in zethrene and dibenzozethrene twisted their backbones, and remarkably influenced their properties. Unlike closed-shell disubstituted derivatives, the parent zethrene and dibenzozethrene are singlet open-shell biradicals, which were studied by variable-temperature 1H NMR, ESR, SQUID and computational methods. Since substituents were observed to affect significantly the biradical properties, the relevant mechanisms were analyzed. The nonlinear optical performance of each of these compounds depends on its π-conjugation and biradical properties. Dibenzozethrenes have larger two-photon absorption cross-sections than zethrenes, as most strongly evidenced by the parent dibenzothrene [ σmax=4323 GM at 530 nm]. [ABSTRACT FROM AUTHOR]

A novel ligand, diethylenetriamine-N,N′,N″-tri(acetyl-p-hydroxybenzoyl hydrazine)-N,N″-bisacetic acid, and its three soluble non-ion transition metal complexes, ML· nH2O (M = Mn, n = 4; M = Co, Ni, n = 2) have been synthesized and characterized on the basis of elemental analysis, molar conductivities,1H NMR, FAB-MS, TG-DTA analysis, and IR methods. In addition, relaxivity of complexes are determined, The relaxivity (R1) of MnL, CoL, NiL, and Gd(DTPA)2–used as control are 6.33, 2.71, 2.60, and 4.34L·mmol−1·s−1, respectively. The spin-lattice relaxivity of MnL are larger than that of Gd(DTPA)2−. The results showed that complex of MnL may be a potential MRI contrast agent with high spin-lattice relaxivity, good solubility, low osmotic pressure due to non-ion complex. [ABSTRACT FROM PUBLISHER]

Thirty symmetrical diaryl urea derivatives were synthesised in moderate to excellent yields from arylamine and triphosgene with triethylamine as a reducing agent for the intermediate, isocyanate. It was significant that part of the products could be collected in almost quantitative yield without column chromatography. The procedure under mild reaction conditions was tolerant of a wide range of functional groups. The structures of the compounds were determined by NMR, MS and X-ray crystallographic analyses. [ABSTRACT FROM AUTHOR]

Maintaining a balance between ATP synthesis and heat generation is crucial for adapting to changes in climate. Variation in the mitochondrial DNA (mtDNA), which encodes 13 subunits of the respiratory chain complexes, may contribute to climate adaptation by regulating thermogenesis and the use of bioenergy. However, studies looking for a relationship between mtDNA haplogroups and climate have obtained mixed results, leaving unresolved the role of mtDNA in climate adaptation. Since mtDNA content can regulate human bioenergy processes and is known to influence many physiological traits and diseases, it is possible that mtDNA content contributes to climate adaptation in human populations. Here, we analyze the distribution of mtDNA content among 27 Chinese ethnic populations residing across China and find a significant association between mtDNA content and climate, with northern populations having significantly higher mtDNA content than southern populations. Functional studies have shown that high mtDNA content correlates with an increase in the expression of energy metabolism enzymes, which may accelerate thermogenesis. This suggests that the significantly higher mtDNA content observed in northern populations may confer a selective advantage in adapting to colder northern climates [ABSTRACT FROM AUTHOR]

Fluorenes and methylene-bridged polyarenes were easily and efficiently synthesized from haloarenes (or aryl triflates) and diarylethynes by a one-pot, two-step procedure. This protocol involves the palladium-catalyzed cycloisomerization and a subsequent base-mediated retro-aldol condensation. A major advantage is that the starting materials need not have ortho functional groups to complete the annulation. The backbone of the designed products was enlarged using dihaloarenes, highly π-conjugated haloarenes, or diarylalkynes. The mechanism of the formation of benzo[a]fluorene was investigated. The bowl-shaped structure of methylene-bridged indenocorannulene was verified by X-ray crystallography. The photophysical and electrochemical properties of the products thus prepared were investigated. [ABSTRACT FROM AUTHOR]

Earth-abundant metal complexes have emerged as promising surrogates of platinum for catalyzing the hydrogen evolution reaction (HER). In this study, we report the design and synthesis of two novel nickel quinolinethiolate complexes, namely [Ni(Hqt) 2 (4, 4′-Z-2, 2′-bpy)] (Hqt = 8-quinolinethiol, Z = H [ 1 ] or CH 3 [ 2 ], bpy = bipyridine). An efficient three-component photocatalytic homogeneous system for hydrogen generation working under visible light irradiation was constructed by using the target complexes as catalysts, triethylamine (TEA) as sacrificial electron donor and xanthene dyes as photosensitizer. We obtain turnover numbers (TON, vs. catalyst) for H 2 evolution of 5923/7634 under the optimal conditions with 5.0 × 10 −6 M complex 1/2 respectively, 1.0 × 10 −3 M fluorescein and 5% (v/v) TEA at pH 12.3 in EtOH/H 2 O (1:1, v/v) mixture after 8 h irradiation (λ > 420 nm). We discuss the mechanism of H 2 evolution in the homogeneous photocatalytic system based on fluorescence spectrum and cyclic voltammetry data. [ABSTRACT FROM AUTHOR]

Zethrene-based condensed arenes dinaphthozethrene and diindenozethrene were synthesized by oxidative cyclodehydrogenation and palladium-catalyzed cyclization of 7,14-diarylzethrenes, respectively. Their structures were analyzed by X-ray crystallography. The photophysical and electrochemical properties of these compounds were investigated. [ABSTRACT FROM AUTHOR]

A range of phenanthrene derivatives were efficiently synthesized by the palladium-catalyzed annulation of 2,2'-diiodobiphenyls with alkynes. The scope, limitations and regioselectivity of the reaction were investigated. The described method was adopted to synthesize 9,10-dialkylphe-nanthrenes, sterically overcrowded 4,5-disubstituted phenanthrenes and phenanthrene-based alkaloids. Reactions of highly methoxy-substituted bjphenyls with 2-(2-propynyl)pyrrolidine and 2-(2-propynyl)piperidine gave 2-(9-phenanthylmethyl)pyrrolidines and 2-(9-phenanthylmethyi)piperidines, respectively. The products were transformed to phenanthroindolizidine and phenanthroquinolizidine alkaloids by the Pictet--Spengler reaction. [ABSTRACT FROM AUTHOR]