A ratiometric two-photon fluorescent probe for the quantification of nitroreductase in hypoxic neurons.

We developed a novel ratiometric two-photon fluorescent probe for the selective and precise detection of nitroreductase (NTR) in neurons. Using this probe, we found that hypoxic stimulation could up-regulate endogenous NTR levels.

Photoredox/Iron Dual-Catalyzed Insertion of Acyl Nitrenes into C-H Bonds.

In this work, the use of -acyloxybenzamides as efficient acyl nitrene precursors under photoredox/iron dual catalysis is reported. The resulting acyl nitrenes could be captured by various types of C-H bonds and S- or P-containing molecules. Mechanism investigations suggested that the formation of the acyl nitrene from the -acyloxybenzamide occurs by a photoredox process, and it is believed that in this redox process oxidative N-H bond cleavage of the -acyloxybenzamide occurs prior to reductive N-O bond cleavage of the -acyloxybenzamide.

Recent advances in higher order rotaxane architectures.

Despite dramatic advances in the template-directed synthesis of archetypal [2]rotaxanes, higher order rotaxanes with multiple molecular components (rings or dumbbells) are relatively daunting subjects owing to their synthetic challenges. With unique interlocked architectures, higher order rotaxanes have found applications in artificial molecular machines. In this feature article, we will focus on the recent advances in higher order rotaxanes with well-defined structures.

Perylenequinone-based "turn on" fluorescent probe for hydrogen sulfide with high sensitivity in living cells.

Hydrogen sulfide (HS) is a kind of gaseous signal molecule in many physiological processes. In order to detect HS, a novel "turn on" fluorescent probe 6,12-dihydroxyperylene-1,7-dione (DPD) was designed and synthesized. The probe DPD is fluorescence silence, while the addition of HS induces an obvious green fluorescence with an obvious color change from dark blue to yellow-green.

CuX-Activated N-Halosuccinimide: Synthesis of 3-Haloquinolines via Electrophilic Cyclization of Alkynyl Imines.

We report an electrophilic cyclization of alkynyl imines to afford polysubstituted 3-haloquinolines using CuX-activated N-halosuccinimdes (NXS) as electrophiles. Control experiments demonstrated that the NXS/CuX system might be more active than single NXS and could be applied in the electrophilic cyclization of electron- deficient substrates.

Complexation of triptycene-derived macrotricyclic polyether with paraquat derivatives, diquat, and a 2,7-diazapyrenium salt: guest-induced conformational changes of the host.

Complexation between a triptycene-derived macrotricyclic polyether containing two dibenzo-[30]-crown-10 cavities and different functionalized paraquat derivatives, diquat, and a 2,7-diazapyrenium salt in both solution and solid state was investigated in detail. It was found that depending on the guests with different terminal functional groups and structures, the macrotricyclic polyether could form 1:1 or 1:2 complexes with the guests in different complexation modes in solution and also in the solid state. Especially, the conformation of the macrotricyclic polyether was efficiently adjusted by the encapsulated guests, which was to some extent similar to substrate-induced fit of enzymes.

7-Hy-droxy-1,2,3,4-tetra-hydro-quinolin-2-one dihydrate.

The asymmetric unit of the title compound, C(9)H(9)NO(2)·2H(2)O, comprises two independent organic mol-ecules and four water mol-ecules of crystallization. The heterocyclic rings are not planar: in one mol-ecule, the C atom bearing the O atom and the adjacent methyl-ene C atom are displaced by 0.320 (3) and 0.

N-(2-{[7-(2-Anilinoeth-oxy)-3,6-dibromo-naphthalen-2-yl]-oxy}eth-yl)aniline.

In the title compound, C(26)H(24)Br(2)N(2)O(2), the central naphthalene system carries two Br atoms and two -CH(2)CH(2)NHC(6)H(5) substituents. The phenyl rings of the latter residues are inclined at 74.17 (17) and 51.

N'-(3-Fluoro-benzyl-idene)-4-hy-droxy-3-meth-oxy-benzohydrazide methanol monosolvate.

In the title compound, C(15)H(13)FN(2)O(3)·CH(3)OH, the dihedral angle between the benzene rings of the benzohydrazone mol-ecule is 5.3 (3)°. The C atom of the meth-oxy group is almost coplanar with its attached ring [deviation = 0.

Synthesis of triptycene-derived macrotricyclic host containing two dibenzo-[18]-crown-6 moieties and its complexation with paraquat derivatives: Li(+)-ion-controlled binding and release of the guests in the complexes.

A new triptycene-derived macrotricyclic host containing two dibenzo-[18]-crown-6 moieties was synthesized and shown to form 1:1 complexes with paraquat derivatives in solution, in which the guests all thread the central cavity of the host. However, it was interestingly found that, depending on the paraquat derivatives with different functional groups, the host can form stable 1:1 or 1:2 complexes in different complexation modes in the solid state, which is significantly different from those of the macrotricyclic host containing two dibenzo-[24]-crown-8 moieties. The formation of the complexes was also proved by the ESI MS and electrochemical experiments.

Complexation of triptycene-based macrotricyclic host toward (9-anthracylmethyl)benzylammonium salt: a Ba2+ selective fluorescence probe.

A new triptycene-based macrotricyclic host containing two dibenzo-30 crown-10 moieties (1) has been synthesized. It could form a 1:2 stable complex 1 x 3(2) with (9-anthracylmethyl)benzylammonium salt (3) in both solution and solid state, in which the 9-anthracyl groups were selectively positioned inside the cavity of the host. Moreover, the complexation and disassociation of complex 1 x 3(2) could be chemically controlled by the addition of base and acid.

Guest-dependent complexation of triptycene-based macrotricyclic host with paraquat derivatives and secondary ammonium salts: a chemically controlled complexation process.

The triptycene-based macrotricyclic host containing two dibenzo-[24]-crown-8 moieties has been found to form stable 1:1 or 1:2 complexes in different complexation modes with different functional paraquat derivatives and secondary ammonium salts in solution and in the solid state. Consequently, the alkyl-substituted paraquat derivatives thread the lateral crown cavities of the host to form 1:1 complexes. It was interestingly found that the paraquat derivatives containing two beta-hydroxyethyl or gamma-hydroxypropyl groups form 1:2 complexes, in which two guests thread the central cavity of the host.

Complexation of triptycene-based cylindrical macrotricyclic polyether toward diquaternary salts: ion-controlled binding and release of the guests.

Triptycene-based cylindrical macrotricyclic polyether 1 has been proved to be an efficient host for the complexation with diquaternary salts in solution and in the solid state. Moreover, it was also found that binding and release of the guest molecules could be easily controlled by the addition and removal of potassium ions.

Erratum: 2-[(E)-(Dimethylamino)methylene-amino]-N-phenylbenzenesulfonamide. Corrigendum.

Corrections are made to the name of the author and the address in Zhong [Acta Cryst. (2007), E63, o4446].[This corrects the article DOI: 10.

Self-assembly of triptycene-based cylindrical macrotricyclic host with dibenzylammonium ions: construction of dendritic [3]pseudorotaxanes.

[reaction: see text] It was found that a cylindrical macrotricyclic host containing two dibenzo[24]crown-8 cavities could self-assemble with two dibenzylammonium salts to form a stable 1:2 complex in solution and in the solid state, in which multiple hydrogen-bonding and pi-pi stacking interactions between the host and the guest played an important role. Furthermore, a series of dendritic pseudorotaxanes were constructed and structurally studied.

Novel triptycene-based cylindrical macrotricyclic host: synthesis and complexation with paraquat derivatives.

[reaction: see text] A novel triptycene-based cylindrical macrotricyclic polyether containing two dibenzo[24]crown-8 cavities has been synthesized and proved to be a highly efficient host for the complexation with paraquat derivatives. Consequently, a new kind of very stable pseudorotaxane-type complex was formed in solution and in the solid state.