Guo-Fang Jiang

Dehydration triggered asymmetric hydrogenation of 3-(α-hydroxyalkyl)indoles

Highly enantioselective hydrogenation of 3-(α-hydroxyalkyl)indoles promoted by a Bronsted acid for dehydration to form a vinylogous iminium intermediate in situ was developed with Pd(OCOCF3)2/(R)-H8-BINAP as catalyst with up to 97% ee. This methodology provides an efficient and rapid access to chiral 2,3-disubstituted indolines.

The Concise Synthesis of Spiro-Cyclopropane Compounds via the Dearomatization of Indole Derivatives

A concise synthesis of spiro-cyclopropane compounds from indole derivatives and sulfur ylides has been developed via a dearomatization strategy. Moreover, the spiro-cyclopropane compounds could be conveniently transformed to rearomatized indole derivatives in the presence of acids.

Toward Covalent Organic Frameworks Bearing Three Different Kinds of Pores: The Strategy for Construction and COF-to-COF Transformation via Heterogeneous Linker Exchange

Covalent organic frameworks (COFs) are an emerging class of crystalline porous organic materials which are fabricated via reticular chemistry. Their topologic structures can be precisely predicted on the basis of the structures of building blocks. However, constructing COFs with complicated structures has remained a great challenge, due to the limited strategies that can access to the structural complexity of COFs. In this work, we have developed a new approach to produce COFs bearing three different kinds of pores. The design is fulfilled by the combination of vertex-truncation with multiple-linking-site strategy. On the basis of this design, a V-shaped building block carrying two aldehyde groups on the end of each branch has been synthesized. Condensation of it with 1,4-diaminobenzene or benzidine leads to the formation of two triple-pore COFs, TP-COF-DAB and TP-COF-BZ, respectively. The topological structures of the triple-pore COFs have been confirmed by PXRD studies, synchrotron small-angle X-ray scattering (SAXS) experiments, theoretical simulations, and pore size distribution analyses. Furthermore, for the first time, an in situ COF-to-COF transformation has also been achieved by heating TP-COF-BZ with 1,4-diaminobenzene under solvothermal condition, which leads to the formation of TP-COF-DAB via in situ replacing the benzidine linkers in TP-COF-BZ with 1,4-diaminobenzene linkers.

Precision Construction of 2D Heteropore Covalent Organic Frameworks by a Multiple‐Linking‐Site Strategy

Integrating different kinds of pores into one covalent organic framework (COF) endows it with hierarchical porosity and thus generates a member of a new class of COFs, namely, heteropore COFs. Whereas the construction of COFs with homoporosity has already been well developed, the fabrication of heteropore COFs still faces great challenges. Although two strategies have recently been developed to successfully construct heteropore COFs from noncyclic building blocks, they suffer from the generation of COF isomers, which decreases the predictability and controllability of construction of this type of reticular materials. In this work, this drawback was overcome by a multiple-linking-site strategy that offers precision construction of heteropore COFs containing two kinds of hexagonal pores with different shapes and sizes. This strategy was developed by designing a building block in which double linking sites are introduced at each branch of a C3 -symmetric skeleton, the most widely used scaffold to construct COFs with homogeneous porosity. This design provides a general way to precisely construct heteropore COFs without formation of isomers. Furthermore, the as-prepared heteropore COFs have hollow-spherical morphology, which has rarely been observed for COFs, and an uncommon staggered AB stacking was observed for the layers of the 2D heteropore COFs.

Two-dimensional dual-pore covalent organic frameworks obtained from the combination of two D2h symmetrical building blocks

A strategy to construct covalent organic frameworks (COFs) bearing two different kinds of pores has been developed, by which two dual-pore COFs were fabricated through the condensation reactions of two D2h symmetrical building blocks. The COFs exhibit good adsorption capacities for CO2 and H2.

Self‐Assembly of Chiral Propeller‐like Supermolecules with Unusual “Sergeants‐and‐Soldiers” and “Majority‐Rules” Effects

Chiral amplification is an interesting phenomenon in supramolecular chemistry mainly observed in complicated systems in which cooperative effect dominate. Herein, chiral, supramolecular, propeller-like architectures have been constructed through coassembly of an achiral disk-shaped molecule and chiral amino acid derivatives driven by intermolecular hydrogen bonding. Both the sergeants-and-soldiers principle and majority-rules effect are applicable in these discrete four-component supermolecules, which are the simplest supramolecular system ever reported that exhibit chiral amplification.

Synthesis of Chiral Pyrazolone and Spiropyrazolone Derivatives through Squaramide-Catalyzed Reaction of Pyrazolin-5-ones with o-Quinone Methides

A bifunctional squaramide-catalyzed reaction of pyrazolin-5-ones with o-quinone methides in situ generated from 2-(1-tosylalkyl)phenols has been successfully developed, providing a facile access to chiral pyrazolones with high enantioselectivities. In addition, the chiral spiropyrazolones with adjacent tertiary and quaternary stereogenic centers can also be obtained through cascade chlorination/cyclization of the chiral pyrazolones.

Construction of two heteropore covalent organic frameworks with Kagome lattices

Two novel covalent organic frameworks (COFs) bearing Kagome lattices have been fabricated through the condensations of a D2h symmetrical tetraaldehyde and C2 symmetrical aromatic diamines of various lengths.

A novel two-photon fluorescent probe for hydrogen sulfide in living cells using an acedan–NBD amine dyad based on FRET process with high selectivity and sensitivity

Two-photon imaging, due to its unique advantage to utilize near-infrared light as the excitation source, has emerged as an important tool for biomedical research. Herein, the first NBD amine based two-photon fluorescence probe L using a FRET strategy was developed for detecting H2S in vitro and in vivo. The probe L not only afforded high selectivity and sensitivity for the detection of H2S, but also displayed a linear response to H2S with a low detection limit of 24 nM. Furthermore, the living cell experiments indicated that L can be effective for the both exogenous and endogenous detection of H2S inside living cells by two-photon fluorescence imaging.

Substituted tetrapyrazolylporphyrins: application in organic light-emitting diodes

Six substituted tetrapyrazolylporphyrins (TAPyPH2), meso-tetrakis(1-phenylpyrazol-4-yl)porphyrin (TPPyPH2), meso-tetrakis[1-(p-tolyl)pyrazol-4-yl] porphyrin ((p-CH3)TPPyPH2), meso-tetrakis[1-(p-methoxyphenyl)pyrazol-4-yl]porphyrin ((p-CH3O)TPPyPH2), meso-tetrakis[1-(p-chlorophenyl) pyrazol-4-yl]porphyrin ((p-Cl)TPPyPH2), meso-tetrakis[1-(p-bromophenyl)pyrazol-4-yl]porphyrin ((p-Br)TPPyPH2) and meso-tetrakis[1-(m-tolyl)pyrazol-4-yl]porphyrin ((m-CH3)TPPyPH2), were synthesized by the condensation of pyrrole with the corresponding substituted formylpyrazole and used as the doping materials in the Organic Light-Emitting Diodes (OLEDs) with hole-transport materials of N,N-diphenyl-N,N-bis (4-methylphenyl)-[1,1-biphenyl]-4,4-diamine (TPD) within a tris(8-hydroxyquinoline) aluminum (Alq3) host layer. Both the electroluminescence properties of these OLEDs and effects of the peripheral substituents of the tetrapyrazolylporphyrins on EL properties of the OLEDs were studied. The tests found that the OLEDs using substituted tetrapyrazolylporphyrins (TAPyPH2) as the dopants had the saturated red emission at a concentration of 1.5 wt.%. The electron-donating groups of tetrapyrazolylporphyrins (for example, p-CH3 and p-CH3O) increased the luminance of OLEDs, while the electron-drawing groups (for example, p-Cl and p-Br) decreased the luminance. The OLEDs using meso-tetrakis(1-phenylpyrazol-4-yl)porphyrin (TPPyPH2) as a dopant showed saturated red emission at 680 nm (CIE coordinates of x = 0.65, y = 0.31) with a luminance of 305 cd/m2 at a driving voltage of 25 V at concentration of 1.5 wt.%. Compared with OLEDs doped by the free-base tetraphenylporphyrin (TPPH2), the OLEDs doped by the tetrapyrazolylporphyrins had better luminance and higher emission efficiency. An explanation for these results was given based on the molecular structure and spectral properties of the porphyrin compounds.