Highly crystalline covalent organic frameworks from flexible building blocks.

Two novel 2D covalent organic frameworks (TPT-COF-1 and TPT-COF-2) were synthesized from the flexible 2,4,6-triaryloxy-1,3,5-triazine building blocks on a gram scale, which show high crystallinity and large surface area. The controllable formation of highly ordered frameworks is mainly attributed to the self-assembly Piedfort unit of 2,4,6-triaryloxy-1,3,5-triazine.

Organic base-promoted enantioselective electrophilic cyanation of ß-keto esters by using chiral phase-transfer catalysts.

Highly enantioselective cyanation of ß-keto esters using hypervalent iodine(iii) as the electrophilic cyanating reagent induced by cinchona alkaloid-based chiral quaternary ammonium salt was demonstrated. Organic bases, especially DMAP, in the chiral phase-transfer catalysis were used to obtain high ees.

Visible light-mediated dehydrogenative ß-arylsulfonylation of tertiary aliphatic amines with arylsulfonyl chlorides.

The novel synthesis of ß-arylsulfonyl enamines has been achieved by visible light-mediated dehydrogenative arylsulfonylation of tertiary aliphatic amines with arylsulfonyl chlorides in moderate yield.

Manganese-catalyzed dehydrogenative [4+2] annulation of N-H imines and alkynes by C-H/N-H activation.

Described herein is a manganese-catalyzed dehydrogenative [4+2] annulation of NH imines and alkynes, a reaction providing highly atom-economical access to diverse isoquinolines. This transformation represents the first example of manganese-catalyzed CH activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition-metal-catalyzed CH activation. Mechanistic studies revealed the five-membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle.

Mn-catalyzed three-component reactions of imines/nitriles, Grignard reagents, and tetrahydrofuran: an expedient access to 1,5-amino/keto alcohols.

An expedient Mn-catalyzed three-component synthesis of 1,5-amino/keto alcohols from Grignard reagents, imines/nitriles, and tetrahydrofuran (THF) is described, which deviates from the classic Grignard addition to imines/nitriles in THF solvent. THF is split and "sewn" in an unprecedented manner in the reaction, leading to the formation of two geminal C-C bonds via C-H and C-O cleavage. Mechanistic experiments and DFT calculations reveal radical and organo-Mn intermediates in the catalytic cycle and the α-arylative ring-opening of THF as the key reaction step.

Thermally/hydrolytically stable covalent organic frameworks from a rigid macrocyclic host.

Two new 2D COFs were synthesized from triformylcyclotrianisylene, which show not only thermal stability but also hydrolytic stability. CTV-COF-1 with smaller pore size stored a high hydrogen level of 1.3 wt% at low pressure, while CTV-COF-2 with larger pore size showed superior carbon dioxide uptake, up to 250 cm(3) g(-1) at 298 K and 50 bar.

Spontaneous chiral resolution directed by symmetry restriction and π-π interaction.

In order to understand and rationally construct homochiral self-assembled structures from racemic molecules, two novel crystalline metal-organic frameworks with chiral cavities were developed. The homochirality of the layers in both MOFs was achieved by forming strong coordinate bonds between the C3-symmetric cyclotriveratrylene and Zn4O(CO2)6 cluster. By changing weak π-π interactions between organic building blocks, the achiral assembly of ZnCTV-1 was successfully transformed into a chiral assembly in ZnCTV-2. This study demonstrated a possible route for designing the synthesis of chiral MOF through weak interactions.

Visible light-induced 3-sulfenylation of N-methylindoles with arylsulfonyl chlorides.

The synthesis of 1-methyl-3-(arylthio)-1H-indoles has been achieved by the photoredox reaction of N-methylindoles with readily available arylsulfonyl chlorides in moderate yields.

Regulating the Conformation of Methylazacalix[6]pyridine by Oligonucleotide BCL-2 2345 and Its Recognition of Hydroxymethylpiperazinofullerene.

Calixaromatics have attracted much attention on molecular recognition owing to their flexible conformations, cavity structures, versatile recognition properties, and functions. However, conformational control of calixaromatics is still a challenging topic in the field of calixaromatics. Therefore, we explore the possibility to control the chirality of achiral calixaromatics, methylazacalix[6]pyridine (abbreviated as MACP6), by templating of DNA. We have found that MACP6 with opposite chirality can be achieved by controlling the secondary structure of bcl-2 2345 DNA. Furthermore, MACP6 with different chirality has been used to recognize fullerene derivatives in aqueous solution. Our results have provided a possible approach to construct chiral calixaromatics.

Rhenium-catalyzed regiodivergent addition of indoles to terminal alkynes.

An efficient rhenium-catalyzed site-switchable addition of indoles to terminal alkynes is described. A variety of bisindolylalkane derivatives are expeditiously synthesized in high yields with excellent regioselectivity. Preliminary mechanistic study sheds light on the observed regiodivergent addition.

Synthesis, structure, fullerene-binding and resolution of C3-symmetric cavitands with rigid and deep cavities.

An efficient palladium-catalyzed Suzuki-Miyaura coupling method involving the reaction between CTV-Br(3) and a variety of aryl and heteroaryl boronic acids in the presence of indolyl phosphane ligands has been developed. This reaction procedure provided a series of C(3)-symmetric aryl-extended rigid cavitands for the first time. X-ray crystal structure analysis revealed that the phenyl substituted cavitand 5a has much larger rim edges and cavity height. This macrocyclic host adopts a linear head-to-tail "hand-shake" self-inclusion arrangement in the crystalline state. The fluorescence of 5a was considerably quenched upon the addition of C(60), with a binding constant of 78,700 ± 2300 dm(3) mol(-1) and a 1:1 stoichiometry according to the Job's plot. The interaction of C(60) with 5a in the excited state is stronger than that with CTV, which could be attributed to more binding sites in the extended arms of 5a. Moreover, optically active C(3)-symmetric cavitands (+)- and (-)-6 were easily obtained with high efficiency through chemical resolution.

Heterogeneous bilayer molecular structure at a liquid-solid interface.

Hexaphenylbenzene (HPB) derivatives, HPB-6a and HPB-6pa, can form a supramolecular network which is stabilized by the intermolecular hydrogen bonding between carboxyl group at an octanoic acid/graphite interface. The observation of the heterogeneous bilayer structure formed exclusively by coronene and HPB-6pa at the octanoic acid/graphite interface is reported. Pronounced selectivity of coronene for the supramolecular networks with different sizes is reflected through the formation of bilayer structure for HPB-6pa network with the introduction of coronene as the guest species, indicating stronger interactions between HPB-6pa and coronene.

Design and construction of an organic crystal with a novel interpenetrated n-Borromean linked topology.

An organic crystal has been designed and constructed by the hydrogen-bond-directed self-assembly of TCA and dpyb, which possesses the large honeycomb net with 5.1 x 5.1 nm cavities and a novel interpenetrated n-Borromean linked topology.

Complexation of a pentiptycene-based tweezer-like receptor with paraquat derivatives: ion-controlled binding and release of the guests.

A new tweezer-like receptor containing a pentiptycene unit and a benzene ring linked by two crown ether chains has been synthesized. It could form stable complexes with paraquat derivatives with different functional groups in solution and in the solid state. It was found that the complexes dissociated upon two one-electron reduction of the bipyridinium ring. Moreover, binding and release of the guest molecules could also be easily controlled by the addition and removal of potassium ion.

Highly efficient and concise synthesis of both antipodes of SB204900, clausenamide, neoclausenamide, homoclausenamide and zeta-clausenamide. Implication of biosynthetic pathways of Clausena alkaloids.

The synthesis of both antipodes of N-methyl-N-[(Z)-styryl]-3-phenyloxirane-2-carboxamide (SB204900), clausenamide, neoclausenamide, homoclausenamide and zeta-clausenamide have been accomplished using (2S,3R)- and (2R,3S)-3-phenyloxirane-2-carboxamides as the starting materials, and SB204900 was found to be a common precursor to other N-heterocyclic clausena alkaloids. Mediated by Brønsted acids under different conditions, for example, SB204900 underwent efficient and diverse alkene-epoxide cyclization, enamide-epoxide cyclization and arene-epoxide cyclization reactions to produce the five-membered N-heterocyclic neoclausenamide, its 6-epimer, the six-membered N-heterocyclic homoclausenamide and the eight-membered N-heterocyclic zeta-clausenamide, respectively, in good to excellent yields. Regiospecific oxidation of neoclausenamide and its 6-epimer afforded neoclausenamidone. Enolization of neoclausenamidone in the presence of LiOH and the subsequent protonation under kinetic conditions at -78 degrees C led to the epimerization of neoclausenamidone into clausenamidone. Reduction of clausenamidone using NaBH(4) furnished clausenamide in high yield.

Peripherally dimethyl isophthalate-functionalized poly(benzyl ether) dendrons: a new kind of unprecedented highly efficient organogelators.

A series of poly(benzyl ether) dendrons, up to the fourth generation, decorated in their periphery with dimethyl esters were divergently synthesized and fully characterized. These dendrons were found to be unprecedented highly efficient organogelators toward various aromatic and polar organic solvents with the critical gelator concentration (CGC) approaching 2.2 mg/mL. The gelation ability was found to be highly dependent on the nature of the peripheral groups, dendron generation, and the dendritic architecture. The large monodisperse dendron G(4) with a globular shape could also form stable gels in several aromatic solvents with relatively high CGCs. A number of experiments (SEM, TEM and AFM imaging, X-ray crystal structure analysis, concentration- and temperature-dependent (1)H NMR spectroscopy, fluorescence spectroscopy, and powder X-ray diffraction) confirmed the self-aggregation of these dendrons, despite the lack of any conventional gelating motifs such as amides, long alkyl side chains, and steroidal groups. The multiple strong pi-pi stacking interactions due to the peripheral dimethyl isophthalate rings and the internal benzyl rings are found to be the key contributor in forming the self-assembled gel.

Rational construction of 2D and 3D borromean arrayed organic crystals by hydrogen-bond-directed self-assembly.

Borromean organic networks: The rigid and trigonal pyramidal molecule, 1,3,5-tris(4-carboxyphenyl)adamantane (TCA), self-assembles into a 2D Borromean linked network by hydrogen bonds. Different linkers (methanol, phenazine, 4,4'-bipyridine, and 4,4'-azopyridine) result in more complex Borromean networks or a 3D polycatenation network.

Molecular encapsulation of a discrete (H2O)32 cluster with S6 symmetry in an organic crystalline supermolecule.

A discrete S6-symmetrical (H2O)32 cluster was encapsulated in the cavity of an organic co-crystalline supermolecule constructed by the co-crystallization of guanidinium and benzenetribenzoate ions through hydrogen bonds, pi-pi and cation-pi interactions.