Synthesis and ultraviolet/aggregation-induced emission investigation of novel tetraphenylvinyl hydrazone derivatives: efficient multimodal chemosensors for fluoride ion

Herein,three novel tetraphenylethylene hydrazone chemosensors TC12,SC16,and TC16 are prepared for the selective detection of F−.Two NH and one C=N units are incorporated into the sensors for better colorimetric responses,whereas the tetraphenyl unit is in charge of the aggregation-induced emission effect.Among them,compounds SC16 and TC16 form stable gels with some organic solvents.All the tetrahydrofuran/H2O solutions of the three compounds exhibit aggregation-induced emission effect,whereby the fluorescence emission increases by varying degrees with the volume of poor solvent water.Moreover,good aggregation-induced emission effects are observed in the self-assembly of SC16 and TC16.As a sample chemosensor,TC12 in tetrahydrofuran responds to F−selectively with high sensitivity,with the colorimetric and fluorometric detection limits of 8.25×10^(−7) mol·L^(-1) and 2.69×10^(−7) mol·L^(-1),respectively.The reversible gel-sol-gel phase transition and color changes indicate that both SC16-dimethyl sulfoxide and TC16-ethyl acetate gels specifically respond to F-with good sensitivity.The detection results are well supported by ultraviolet-visible spectroscopy,fluorescent spectroscopy,and 1H nuclear magnetic resonance.More importantly,the driving forces of gelation are visually clarified through the single crystal X-ray analysis of compound TOMe.

Organogelators based on p-alkoxylbenzamide and their self-assembling properties

A series of p-alkoxylbenzamides featuring a long alkyl chain have been synthesized and are readily to form stable gels in a variety of organic solvents. Their selfassembly properties and structure-property relationship were investigated by scanning electron microscopy, X-ray diffraction, IH nuclear magnetic resonance, and Fourier transform infrared spectroscopy. The gels formed were multi-responsive to environmental stimuli such as temperature and fluoride anion. The results show that a combination of hydrogen bonding, n-n stacking and van der Waals interaction result in the aggregation of palkoxylbenzamides to form three-dimension networks, depending on the length of the long alkyl chain.

Novel 1,2,3-triazole-based compounds： Iodo effect on their gelation behavior and cation response

Two new series of 1,2,3-triazole derivatives, with and without iodo substitution, were synthesized and their gelation properties were measured. It was found that the iodo substitution at position 5 of triazole ring could greatly enhance the gelation ability. Scanning electron microscopy and X-ray diffraction reveal that the structures of the organogels from iodo and hydrogenous gelators are totally different, lodo gels are selectively responsive to the stimuli of Hg2＋, whereas hydrogenous gels can respond to Hg2＋ and Cu2＋. Moreover, the reversible gel-sol transition of hydrogenous gels can be controlled by redox reaction or tuned with suitable chemicals. The single crystal analysis of reference compound （C2） suggests that there are intermolecular and intramolecular non-classical hydrogen bonding interactions but no π-π interaction in hydrogenous gelator. The great difference between the two series of compounds results from the iodo effect and implies the existence of halogen bonding interaction in the iodo compounds.

Supramolecular self-assembly of two-component systems comprising aromatic amides/Schiff base and tartaric acid

The gelating properties and thermotropic behaviors of stoichiometric mixtures of aromatic amides 1,2,and the aromatic Schiffbase 3 with tartaric acid(TA)were investigated.Among the three gelators,2-TA exhibited superior gelating ability.Mixture 2-TA exhibits a smectic B phase and an unidentified smectic mesophase during both heating and cooling runs.The results of Fourier transform infrared spectroscopy and X-ray diffraction revealed the existence of hydrogen bonding and rc-ninteractions in 2-TA systems,which are likely to be the dominant driving forces for the supramolecular selfassembly.Additionally,it was established that all of the studied gel self-assemblies and mesophases possess alamellar structure.The anion response ability of the tetrahydrofuran gel of 2-TA was evaluated and it was found that it was responsive to the stimuli of F,Cl,Br,I,AcO.

Synthesis and properties of novel organogelators functionalized with 5-iodo-1,2,3-triazole and azobenzene groups

Two series of 5-iodo-l,2,3-triazole derivatives containing azobenzene group（s） were synthesized and their gelling properties were tested. Those containing two azobenzene groups （B series） have better gelation performance than those containing one azobenzene group （A series）. The microstructure of organogels and the driving force of gelation were investigated by scanning electron microscopy and 1H NMR, respectively. It was found that π-π stacking, van der Waals interaction, and dipole-dipole interaction were the main forces of gelation. All the tested organogels are photoresponsive and those from B series are smarter than that from A series. Henry δp-δb diagrams of compounds A1, A2, and B2 were constructed on the basis of their gelation performance and the Hansen solubility parameters of related solvents. The constructed Henry δp-δh diagrams can be used to estimate the behavior of three compounds in any untested solvent.

A highly efficient methodology for the preparation of N-methoxycarbazoles and the total synthesis of 3,3'-[oxybis(methylene)]bis(9-methoxy-9H-carbazole)

A convenient and highly efficient method is described for the synthesis of N-methoxycarbazole derivatives,including those with sterically demanding,benzannulated,or strongly electron-donating or-withdrawing substituents.Various N-methoxycarbazole derivatives were directly prepared in good-to-moderate yields by the Pd_(2)(dba)_(3)CHCl_(3)/9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene-catalyzed reactions of the corresponding dibromobiphenyl compounds and methoxyamine.Based on this methodology,the first total synthesis of 3,3′-[oxybis(methylene)]bis(9-methoxy-9H-carbazole),an antimicrobial dimeric carbazole alkaloid previously isolated from the stem bark of Murraya koenigii,was achieved in 18% yield over seven steps from 1,2-dibromobenzene.

Synthesis of C1-symmetric primary-secondary diamines and their application in the enantioselective Henry reaction

Two new Cl-symmetric primary-secondary diamines were synthesized via the reaction of （S,S）-1,2- diphenyl ethylene diamine with 3,5-ditert-butyl salicylal- dehyde and salicylaldehyde, respectively, followed by reduction with NaBH4. The combination of the ligand from 3,5-ditert-butyl salicylaldehyde with CuBr could effciently catalyze the Henry reaction to afford β- nitroalkanols in moderate to good yields （up to 87%） and high enantioselectivities （up to 88% ee）. A possible mechanism of the reaction was proposed.

Enantioselective Organocatalytic Aza-Michael Additions of Phthalimide Derivatives to α,β-Unsaturated Aldehydes

Phthalimide derivatives as nitrogen nucleophiles with α,β-unsaturated aldehydes for asymmetric aza-Michael additions have been reported. The reactions proceed smoothly to afford corresponding Michael adducts in good yields （up to 98%） and enantioselectivities （up to 95% ee）.