Juli Jiang

Pillar[5]arene-based supramolecular polypseudorotaxanes constructed from quadruple hydrogen bonding

Novel linear supramolecular polypseudorotaxanes constructed from bifunctional ureidopyrimidinone (UPy) pillar[5]arene as the wheel and alkyl diamine as the axle were successfully prepared. This supramolecular polymer was stabilized by the combination of two different non-covalent interactions: quadruple hydrogen bonding and pillararene-based host–guest interactions.

Cu-Catalyzed Cross-Dehydrogenative Coupling Reactions of (Benzo)thiazoles with Cyclic Ethers

Copper-catalyzed cross-dehydrogenative coupling (CDC) reactions of (benzo)thiazoles with cyclic ethers were developed under mild conditions. In particular, the formation of C-C bonds via the CDC reactions between non-benzo-fused azoles and ethers are reported for the first time. In addition, the acetals, known as the masked 2-thiazolecarboxaldehydes, could be successfully obtained by this CDC reaction. The preliminary mechanism and supportive DFT calculations are discussed as well.

Novel self-assembled dynamic [2]catenanes interlocked by the quadruple hydrogen bonding ureidopyrimidinone motif

Novel dynamic [2]catenanes interlocked by the quadruple hydrogen bonding ureidopyrimidinone (UPy) motif have been developed. The dynamic catenation process was due to the selective cyclization of bifunctional UPy molecules over a wide concentration range with the assistance of the cyclobis(paraquat-p-phenylene) (CBPQT4+4+) macrocycle. The self-assembled [2]catenanes were stabilized by a combination of different non-covalent interactions comprising quadruple hydrogen bonding and host–guest interactions. This type of non-covalent bonded catenane is the first one interlocked by multiple hydrogen bonding interactions instead of metal–ligand interactions.

Ligand-Free Copper-Catalyzed Regioselective C-2 Arylation of Imidazo[2,1-b]thiazoles

An effective, regioselective C-2 arylation of imidazo[2,1-b]thiazoles catalyzed by Cu(I) has been developed. This arylation proceeded smoothly without promotion of the ligands, and various functional (22 samples) groups were well tolerated. Preliminary mechanistic studies of this arylation are also reported.

Supramolecular polymers based on a pillar[5]arene-fused cryptand: design, fabrication and degradation accompanied by a fluorescence change

Novel linear supramolecular polymers based on a pillar[5]arene-fused cryptand have been constructed easily and conveniently, in which three orthogonal interactions: quadruple hydrogen bonding, cryptand-based host–guest recognition, and pillar[5]arene-based host–guest interaction were combined together. Furthermore, the resulting linear supramolecular polymers can be effectively depolymerized accompanying a fluorescence change by the addition of another competitive cryptand host.

A Phosphine Oxide Functional Group Based [2]Rotaxane That Operates as a Multistable Molecular Shuttle.

A switchable [2]rotaxane based on a pyridinediamide crown ether macrocycle and a thread bearing phosphine oxide, urea, and dibenzylammonium functional groups was successfully developed and characterized by (1) H NMR and 2D NMR spectroscopy, mass spectrometry, and single-crystal analysis. The three recognition sites in the [2]rotaxane were sorted from strong to weak, according to their bonding abilities, so that the macrocycle could move along the thread from one side to the other in a directional way, operating as a multistable molecular shuttle.

Synthesis, chemo-selective properties of substituted 9-aryl-9H-fluorenes from triarylcarbinols and enantiomerical kinetics of chiral 9-methoxy-11-(naphthalen-1-yl)-11H-benzo[a]fluorene

9-Aryl-fluorenes were synthesized conveniently from triarylcarbinols in the presence of TsOH. Notably, the orientation of the intramolecular aromatic substitution reaction was dictated by the nature of the substituents on the aryl rings of triarylcarbinols, owing to electronic and conjugated effects. In particular, triarylcarbinols with (3-methoxy)phenyl and naphthalenyl groups formed benzo[a]fluorenes selectively. Moreover, 9-methoxy-11-(naphthalen-1-yl)-11H-benzo[a] fluorene (2g), with a center of chirality, exists as a mixture of diastereoisomers, due to the restricted rotation of a C–C single bond. First-order rate constants for the enantiomerization of 2g in DMSO were obtained over the temperature from 297 K to 393 K, and thermodynamic parameters were determined as ΔH‡ = 99.7 kJ mol−1, ΔS‡373 K = 37.7 J mol−1 K−1, and ΔG‡373 K = 85.6 kJ mol−1 by Eyring plot analysis.

Density Functional and Kinetic Monte Carlo Study of Cu-Catalyzed Cross-Dehydrogenative Coupling Reaction of Thiazoles with THF

Cu-catalyzed cross-dehydrogenative coupling (CDC) reaction of thiazoles with THF has been studied with the density functional theory method and kinetic Monte Carlo (kMC) simulations. Our results show that the previously proposed concerted metalation-deprotonation mechanism is unfavorable. On the basis of the DFT calculation and kMC simulation results, a new mechanism is proposed. In the favorable mechanism, the Cu(II) catalyst first combines with the thiazoles, forming an organocopper species that then binds to the THF radical. The rate-limiting step, C-C bond formation, is realized through an intramolecular structural rearrangement. The Cu catalyst works as a matchmaker to render the C-C bond formation. Kinetic Monte Carlo simulations demonstrate that one should be careful with the conclusions drawn simply from the calculated barriers.

Self-locked dipillar[5]arene-based pseudo[1]rotaxanes and bispseudo[1]rotaxanes with different lengths of bridging chains

By condensation reactions of pillar[5]arene derivatives and alkylenediamines with different lengths of alkyl chains, self-locked dipillar[5]arene-based pseudo[1]rotaxanes and bispseudo[1]-rotaxanes were obtained, which were characterized via 1D NMR, 2D NMR, and X-ray analyses. It was found that the lengths of alkyl chains of alkylenediamines played crucial roles in forming these self-locked molecules.

A Four-Armed Unsymmetrical Cryptand: From Two Different Host–Guest Interactions to Responsive Supramolecular Polymer

By linking BMP32C10 and DB24C8 motifs together, a four-armed cryptand 1 is synthesized successfully, in which BMP32C10 motif can bind paraquat 2 while DB24C8 motif can complex dibenzylammonium salt 3 in spite of the electrostatic repulsion between guests 2 and 3. The base/acid-responsive supramolecular polymer is constructed further via two kinds of host-guest interactions between cryptand 1 and two homoditopic paraquat 4 and dibenzylammonium salt 5 similar to guests 2 and 3.