A fluorescent and colorimetric receptor (L) for specific recognition of TNP was described. The origins of this remarkable affinity was disclosed by the crystal structure of corresponding host-guest complex L·TNP.

This work illustrates the reductive coupling of electron-rich aryl halides with tertiary alkyl halides under Ni-catalyzed cross-electrophile coupling conditions, which offers an efficient protocol for the construction of all carbon quaternary stereogenic centers. The mild and easy-to-operate reaction tolerates a wide range of functional groups. The utility of this method is manifested by the preparation of cyclotryptamine derivatives, wherein successful incorporation of 7-indolyl moieties is of particular interest as numerous naturally occurring products are composed of these key scaffolds. DFT calculations have been carried out to investigate the proposed radical chain and double oxidative addition pathways, which provide useful mechanistic insights into the part of the reaction that takes place in solution.

A general approach (oxyanion-Cope strategy) for the synthesis of sarpagine/ajmaline indole alkaloids has been developed. (+)-Ajmaline 1 and alkaloid G 2 as well as norsuaveoline 3 have been synthesized from d-(+)-tryptophan in enantiospecific fashion via the asymmetric Pictet−Spengler reaction and a stereocontrolled oxyanion-Cope rearrangement as key steps. The synthesis of these indole alkaloids employed a stereospecific Pictet−Spengler/Dieckmann protocol to prepare the key intermediate, (−)-N b-benzyl tetracyclic ketone (7a or 7b). This ketone was converted into α,β-unsaturated aldehyde (8a or 8b) and further transformed into (+)-ajmaline 1 and alkaloid G 2 as well as norsuaveoline 3. It was also found that reduction of 29 can be done stereospecifically to form the 2-epidiacetylajmaline derivative 30 which has the same configuration at C(2) as that of quebrachidine and of the bisindole alstonisidine. The ring closure reaction (from 27 to 28) to form the sarpagine skeleton was completed in 91% yield. It should now be possible to prepare the antipode of (+)-ajmaline via this approach for biological screening.

A nonsulfur probe based on a 1,8-naphthalimide and alkyne conjugate for the ratiometric fluorescent sensing for Hg(2+) and Au(3+) through the tuning of pH in different aqueous solutions is described. This work provides a novel reaction-based approach for selective recognition of these two ions with significant change of fluorescence color and constitutes the first ratiometric case for Au(3+).

The enantiospecific total synthesis of talpinine 1 and talcarpine 2 has been accomplished from D-(+)-tryptophan in 13 steps (11 reaction vessels) in 10% and 9.5% overall yields, respectively. Moreover, this synthetic approach has been employed for the improved synthesis of alstonerine 3and anhydromacrosalhine-methine 4 in 12% and 14% overall yield, respectively. A convenient synthetic route for the enantiospecific, stereospecific preparation of the key intermediate (-)-N(a)-H, N(b)-benzyl tetracyclic ketone 15a via the asymmetric Pictet-Spengler reaction on a multihundred-gram scale has been developed. A diastereocontrolled (>30:1) anionic oxy-Cope rearrangement and the intramolecular rearrangement to form ring-E and an N(b)-benzyl/N(b)-methyl transfer reaction also served as key steps. This general approach can now be utilized for the synthesis of macroline/sarpagine related indole alkaloids and their antipodes for biological screening.

We report the storage capacities and separation selectivity of an rht-type s-heptazine-based metal organic framework (MOF), [Cu3(TDPAH)(H2O)3]·13H2O·8DMA, 1, (where TDPAH is 2,5,8-tris(3,5-dicarboxylphenylamino)-s-heptazine and DMA is N,N-dimethylacetamide) for C2 hydrocarbons and CO2 over CH4. MOF 1 displays the highest C2H2/CH4 selectivity of 80.9 as well as record high C2H4 and C2H6 adsorption enthalpies. Theoretical calculations reveal that s-heptazine and NH groups within the framework have synergistic effects on CO2 binding.

The reaction-based relay recognition of fluoride and cyanide anions was demonstrated for the first time, with rapid response and unique triple (fluorescence color, intensity and absorption band) output modes in either of two sequential sensing events. Ratiometric determination of these two anions by fluorescence and/or absorbance spectra is also achieved.

A new bifunctional probe based on a pyrene-amino acid conjugate for the differential response of Al(3+) and H(+) was demonstrated for the first time. Interestingly, two solvent-dependent sensing mechanisms for Al(3+), which feature a ratiometric change from excimer to monomer in CH(3)OH and a turn-on response in water, are also disclosed.