Search

The progress in design and synthesis of biobased covalent adaptable networks has been reviewed and their opportunities and challenges for future development are proposed.

Transition metal doping effectively tuned the photochemical properties of titanium-oxo clusters {Ti2Mn4}, {Ti8Co5} and {Ti12Cd5}.

A thermo-responsive MOF has been designed as a highly efficient Pickering emulsifier to stabilize the H2O2-in-oil emulsion. The resultant emulsion displayed good catalytic performance in epoxidation of olefins and easy catalyst-product separation.

Thermosets have many advantages such as excellent mechanical properties, dimensional stability and environmental resistance, but suffer from unsustainability because they are difficult to recycle and overdependent on petroleum chemicals.

The design and fabrication of highly efficient artificial light-harvesting systems (LHSs) are of great importance in supramolecular chemistry and materials science. Benefitting from the convenient construction process of supramolecular self-assembly, herein, a dual-donor artificial LHS was efficiently constructed through hierarchical self-assembly approaches involving metal–ligand coordination interactions, host–guest interactions and hydrophobic interactions. Notably, compared to the model single-donor artificial LHS with only one donor chromophore, the prepared dual-donor artificial LHS exhibited higher energy transfer efficiency and antenna effects. This research provides an efficient strategy for the construction of artificial LHSs with high energy transfer efficiency and antenna effects.

The photocatalytic gas-solid reaction has been regarded as a powerful mean to solve the environmental pollution and energy crisis. However, problems such as catalyst poisoning, low efficiency of reaction, and uncontrollable selectivity are still unsolved restricting the development of photocatalysis. Therefore, it is of significant importance to reveal and elucidate the reaction mechanisms of gas-solid photocatalysis. Herein, five major types of gas-solid photocatalytic reactions including oxidation of NOx, volatile organic compounds (VOCs), NH3 and reduction of CO2, N2 are discussed and summarized. It involves the composition and basic properties of gas molecules, the process of adsorption and activation, and various reaction pathways. Finally, some prospective viewpoints for future development on gas-solid photocatalysis are put forward for further improvements.

A series of fully conjugated macrocycles Mn (n = 4–7) consisting of N-(3,5-di-tert-butyl-4-methoxyphenyl) substituted carbazole (Cz-Ar) were successfully synthesized. The aryl carbazole and macrocycle M4 can be readily oxidized and the corresponding radical cation species were found to be highly stable. Moreover, macrocycle M5 was found to form 1 : 1 stoichiometric complexes with fullerenes C60 and C70 with association constants as high as (8.38 ± 0.33) × 104 M−1 and (7.64 ± 0.26) × 104 M−1, respectively.

A catalytic asymmetric synthesis of 3,4-dihydrocoumarins with adjacent tertiary–quaternary stereocenters by 1,6-addition/transesterification cascade reaction of α-isocyanoacetates with ortho-hydroxyphenyl-substituted para-quinone methides (p-QMs) has been developed. Using a combination of dihydroquinidine-derived aminophosphine and silver nitrate as a binary catalytic system, moderate to good yields, excellent diastereoselectivities (>20 : 1 dr) and good to excellent enantioselectivities (up to 94% ee) were achieved for a wide range of isocyanoacetates and p-QMs.

An efficient organocatalytic asymmetric tandem conjugate addition-protonation of α-substituted isocyanoacetates to 2-chloroacrylonitrile catalyzed by dihydroquinine-derived thiourea has been investigated, affording the corresponding adducts with two non-adjacent tertiary-quaternary stereocenters in excellent yields (up to 99%) along with good to excellent diastereo- and enantioselectivities (up to 20 : 1 dr, up to 95% ee) under mild conditions. The adduct can also be transformed into chiral γ-lactam by synthetic transformations.

Herein, we present the successful preparation of a new family of porphyrin-functionalized coordination star polymers through the combination of coordination-driven self-assembly and post-assembly polymerization. Their ordered self-assembly behaviour in water and potential applications in photodynamic therapy have been demonstrated.

An efficient organocatalytic asymmetric formal [3 + 2] cycloaddition reaction of α-aryl isocyanoacetates with N-aryl or alkyl substituted itaconimides catalyzed by a dihydroquinine derived squaramide catalyst has been investigated, which affords the corresponding spiropyrroline succinimide derivatives with two non-adjacent quaternary–quaternary stereocenters in moderate to good yields (up to 82%) with moderate to excellent diastereoselectivities (up to >20 : 1 dr) and excellent enantioselectivities (90–>99% ee) under mild conditions.

Facile synthesis of diverse rotaxanes was successfully realized through a simple and efficient supramolecular transformation strategy. Starting from an organometallic [3]rotaxane with a platinum-acetylide moiety as the bridge moiety and transformation site, employing a simple phosphine ligand exchange and sequential reductive elimination reactions resulted in the successful preparation of various rotaxanes with diverse structures and properties.

pseudo[1]Catenane 3 is in a self-included conformation in chloroform, but in dichloromethane, it exists in an equilibrium between the self-included conformational state and a de-threading one. The planar chirality inversion of 3 can be triggered by the host-guest complexation of 3 with adiponitrile G, but the extent of such chiral switching depends on the length of self-included bis(pyrazin-2-yloxy)alkane chains in 3 - longer chains are more favored than shorter ones in the inversion.

We have developed an efficient diastereo- and enantioselective Mannich/cyclization cascade reaction of α-substituted isocyanoacetates with 4-aryl-3-carbonyl-1,2,5-thiadiazole-1,1-dioxide type cyclic sulfamide ketimines cooperatively catalyzed by cinchona alkaloid-derived squaramide and AgOAc. The corresponding optically active 2,3,3a,4-tetrahydroimidazo[1,5-b][1,2,5]thiadiazole-1,1-dioxide derivatives were obtained in excellent yields (up to 99%) and good to excellent stereoselectivities (up to >20 : 1 dr, up to 94% ee).

Mono-phosphines (L1 and L2) and diphosphines (L3 and L4) with typical π-acceptor character were prepared and applied in Ir(I)-catalyzed N-alkylation of amines with alcohols. It was found that the π-acceptor character of the applied phosphines is closely correlated to the catalytic efficiency of the [Ir(COD)Cl]2 complex for this green reaction. Compared to PPh3 as the typical σ-donor (i.e. with poor π-acceptor character), L1–L4 all resulted in the efficient N-alkylation of aniline to benzyl-aniline. While L1–L4 coordinated to the Ir(I)-catalyst, the consolidated Ir–P linkages due to π-backdonation could well protect the Ir-catalyst against deactivation, giving rise to the N-alkylation of aniline. On the other hand, the stabilized Ir-catalyst with the involvement of L2 could be recycled successfully for at least 4 runs in the ionic liquid of [MePh3P]Br without the detectable leaching of Ir and P elements in the organic products.

A two-dimensional porous framework SHU-1 could undergo solvent-induced structural transformations to SHU-1a in methanol and SHU-1b in water. SHU-1, SHU-1a and SHU-1b showed selective adsorption towards malachite green.

A series of ionic phosphonium-based aminophosphines L1–L3 were prepared and fully characterized, in each of which the involved bifunctional moieties of the phosphine fragment and Lewis acidic phosphonium were linked together by stable chemical bonds and bridged by one N-atom. The molecular structure of the L2-ligated Rh-complex (Rh-L2) indicated that such bifunctionalities were well retained without incompatibility problems. Investigations on co-catalysis over L1–L3 showed that L3 exhibited the best sequential catalysis for both hydroformylation and acetalization. The phosphine fragment in L3 was responsible for hydroformylation together with the Rh-complex and the phosphonium acted as the Lewis acidic catalyst in charge of acetalization. The L3–Rh(acac)(CO)2 system also exhibited good generality to hydroformylation–acetalization of a wide range of olefins in different alcohols.

A highly efficient and stable Rh–P catalytic system in the RTIL of [PEmim]BF4 was developed for the biphasic hydroformylation of 1-octene by using the diphosphine-functionalized ionic liquid (FIL) of 2. While 2-Rh(acac)(CO)2 was immobilized in [PEmim]BF4 (solvent), a typical biphasic catalysis was fulfilled with advantages of facile separation and recycling ability – 9 runs without any loss of activity. It was found that not only the acquired π-acceptor character of 2, but also the synergetic role of the piperidyl group in [PEmim]BF4 as an N-containing donor, cooperatively contributed to the efficient hydroformylation due to the facilitated formation and stability of the Rh-H active species (ν 2045 cm−1). This was supported by the in situ high-pressure FT-IR spectral analysis.

A novel ionic bi-functional ligand of L2 containing a phosphine and a Lewis acidic phosphonium with I− as the counter-anion was prepared and fully characterized. The molecular structure indicated that the bi-functionalities in L2 were well retained without the incompatibility problem for quenching of the acidity of the phosphonium cation by the Lewis basic phosphine fragment or the anionic I− when the incorporated phosphine fragment and the Lewis acidic phosphonium were strictly located in the confined cis-positions. The co-catalysis over L2–Rh(acac)(CO)2 in the ways of synergetic catalysis and sequential catalysis was successfully fulfilled for one-pot hydroformylation–acetalization, which proved not to be the result of the simple mixture of the mono-phosphine (L4) and the phosphonium salt (L4′). In L2, the phosphonium not only acted as a Lewis acid organocatalyst to drive the sequential acetalization of aldehydes, but also contributed to the synergetic catalysis for the preceding hydroformylation through stabilizing the Rh-acyl intermediate with the phosphine cooperatively. The L2-Rh(acac)(CO)2 system is also generally applied to hydroformylation–acetalization of a wide range of olefins in different alcohols. Advantageously, as an ionic phosphonium-based ligand, L2 could be recycled for 7 runs with Rh(acac)(CO)2 together in RTIL of [Bmim]BF4 without obvious activity loss or metal leaching.

The combination of phosphine-ligated Pd catalysis and phosphonium(V) [corrected] Lewis acid catalysis has been developed for the carbonylative Sonogashira reaction using phosphino-phosphonium [corrected] salts (L1-L4) as bifunctional ligands, in which the Lewis acidic phosphonium(V) [corrected] cations can form secondary bonds with O atoms (in C=O) to cooperatively stabilize Pd-acyl intermediates.

In this study, we reported an epitope imprinting method on the surface of core–shell magnetic nanoparticles (NPs) for the recognition of target bovine serum album (BSA). The epitope was selected as the template molecule from the nonapeptide of surface-exposed C-terminus of BSA. The core–shell magnetic epitope molecularly imprinted polymers (Fe3O4@EMIPs) exhibited a specific capture activity for the corresponding target protein, BSA. The magnetic NPs made it easy to separate the imprinted material from solution by an external magnetic field, and the thin imprinted layer presented fast kinetics for the rebinding of the target protein. Moreover, the Fe3O4@EMIPs could separate BSA from the bovine blood sample. The epitope imprinting approach combined with magnetic NPs provided an easy and fast method for the specific recognition of BSA.

A simple and versatile fluorescent dye NPS based on 1,8-naphthalimide was successfully designed and prepared. It was found that NPS exhibited excellent selectivity for Hg2+ over many other metal ions including Zn2+, Mn2+, Ba2+, Ni2+, Cu2+, Co2+, Pb2+, Mg2+, Cd2+, Fe2+, Al3+, Ag+, Na+, and Li+. In particular, NPS displayed a significant fluorescence “turn-on” to Hg2+ in aqueous solution and living cells, which could be potentially used for quantification of Hg2+. Moreover, two model compounds were rationally designed and synthesized, from which further insight into the sensing mechanism and binding mode of NPS with Hg2+ was obtained. Surprisingly, NPS exhibited interesting twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AIE) behaviours in aqueous solution.

A facile and efficient approach for preparation of ionic liquid functionalized silica-capped CdTe QDs (CdTe/SiO2/IL) was proposed in this work. The imidazolium-based ionic liquid N-3-(3-trimethoxysilylpropyl)-3-methyl imidazolium chloride was introduced and anchored on the surface of silica-capped CdTe QDs by the sol–gel technique, which played the role of a recognition element due to the covalent coordination binding between the heme group of hemoprotein and the imidazolium cation in the ionic liquid. The synthetic CdTe/SiO2/IL was further characterized by elemental analysis, transmission electronic microscopy (TEM), X-ray photoelectron spectra (XPS) and Fourier transform infrared spectroscopy (FT-IR). Combining the merits of the fluorescence property of the QDs and the covalent interaction of the ionic liquid with hemoproteins, the CdTe/SiO2/IL exhibited high adsorption capacity and good specificity toward hemoproteins and also was successfully applied in the fluorescence detection of hemoprotein in biological fluid. The strategy provided a promising way to fabricate functionalized fluorescence materials as biomedical/chemical sensors for the separation and detection of hemoproteins in proteomics research.

New silver(i) double salts (Ag(2)C(2))(AgCF(3)CO(2))(8)(3-pyCONH(2))(2)(H(2)O)(4) (1), [(Ag(2)C(2))(AgCF(3)CO(2))(4)(4-pyCONH(2))(H(2)O)].H(2)O (2), (Ag(2)C(2))(AgCF(3)CO(2))(6)(3-pyCONH(2))(4) (3), (Ag(2)C(2))(AgCF(3)CO(2))(6)(3-pyCN)(2) (4) and (Ag(2)C(2))(AgCF(3)CO(2))(4)(4-pyCN)(2) (5) (n-pyCONH(2) is pyridine-n-carboxamide, n-pyCN is n-cyanopyridine; n=3, 4) have been synthesized by the hydrothermal method. All five compounds contain polyhedral silver(i) cages each encapsulating a C(2)(2-) dianion. Compounds 1, 3 ,4 and 5 exhibit three-dimensional structures, whereas compound 2 is a two-dimensional network. The structure of 1 is constructed from the linkage of a branched-tree architecture via hydrogen bonds. Unlike 4 and 5, which involve the connection of n-cyanopyridine (n=3, 4) with silver columns, 3 results from the linkage of discrete silver cages via pyridine-3-carboxamide.

Correction for ‘Guest-regulated chirality switching of planar chiral pseudo[1]catenanes’ by Ya-Fen Yang et al., Org. Biomol. Chem., 2018, DOI: 10.1039/c8ob00156a.

We report the first organocatalytic activation of monofluorinated silyl enol ethers 1, by nucleophilic tertiary amine catalysis, to develop asymmetric reactions for the construction of fully substituted chiral carbons featuring a C–F bond. Accordingly, a highly stereoselective Mukaiyama-aldol reaction of isatins to furnish hydroxyoxindoles bearing two adjacent tetrasubstituted carbon stereocenters is developed.

A pH and temperature dual-responsive macroporous protein imprinted cryogel was synthesized by a facile “one-pot” method using N-isopropylacrylamide (NIPAAm) and 4-vinylphenylboronic acid (p-VPBA) as the main functional monomers. The smart molecularly imprinted polymers (MIPs) could recognize the target glycoprotein (ovalbumin (OB) as a template) dynamically and reversibly. The morphologies and features of the cryogels were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The rebinding and swelling experiments showed that the MIP cryogels could respond quickly to temperature and pH. Various parameters such as the pH value of the protein solution, adsorption temperature, and the rebinding time were optimized. Under the optimal conditions, a higher adsorption capacity and imprinting factor of the MIP cryogel were achieved, and were found to be 21 mg g−1 and 3.4, respectively. Moreover, the MIP cryogel exhibited good selectivity and acceptable regeneration capacity. A real sample analysis further demonstrated its feasibility for the target protein separation. These excellent performances suggested that the obtained imprinted cryogel should be a promising candidate for recognition and separation of OB.

Solvothermal reactions of a tricarboxylate ligand 5-(4-carboxybenzoylamino)-isophthalic acid (H3L), dipyridyl linkers (bpe, bpa and bpy) and divalent metal ions (Co2+, Cd2+, Zn2+ and Ni2+) provided a highly efficient approach to the syntheses of multi-dimensional framework materials containing interesting structural motifs: [Co3L2(bpe)4]·2DMF·2H2O (1), [Cd3L2(bpe)4]·3H2O (2), [Zn2L(OH)(bpe)]·5.5H2O (3), [Co7L4(bpa)2(OH)2(H2O)4]·4H2O (4), Ni(HL)(bpa)(H2O) (5) and [Zn2(HL)2(bpy)2(H2O)2]·(bpy)·6H2O (6) (bpe = 1,2-bis(4-pyridyl)ethene, bpa = 1,2-bis(4-pyridyl)diazene, bpy = 4,4′-bipyridine). Solids 1 and 2 are isostructural and each features a three-dimensional (3D) pillar-layer architecture generated from bpe-pillared M-L3− layers. Complex 3 has a 3D structure in which the secondary building unit (SBU) is a rare example of a tetranuclear Zn4(μ3-OH)2(COO)6(bpe)4 unit, whereas 4 exhibits an interesting sandwich-shaped architecture with a trimeric unit [Co3(COO)4(OH)(N2)] serving as the SBU. Complex 5 provides an unusual example of a (4,4) grid layer structure bearing free carboxylic acid (–COOH) units. The layered structure of 6 is generated from hydrogen bonded [Zn(HL)(bpy)(H2O)] chains, with free bpy and guest water molecules accommodated inside. Furthermore, the thermal behavior, powder X-ray diffraction (PXRD) and solid state photoluminescence properties correlated with the corresponding structural features were investigated.

A 1,3-alternate conformational oxacalix[2]arene[2]pyrazine, 1, made up of two tetrahedrally oriented –COOH functions and two upper rim pyrazinyl nitrogen atoms, self-assembles into an unprecedented six-fold interpenetrated diamondoid network via intermolecular hydrogen bond interactions. Disordered guest molecules could be included in the hydrophobic channels presented in the supramolecular aggregates.

Cyclooligomerization of 2,6-dichloropyrazine 4 and benzyl 2,3-dihydroxybenzoate 5 under microwave irradiation resulted in a racemic pair of ester functionalized ortho-linked oxacalix[2]benzene[2]pyrazine 6, which was further transformed to the corresponding racemic carboxylic acid functionalized ortho-linked oxacalix[2]benzene[2]pyrazine 3. Both enantiomers of 3 adopt 1,3-alternate conformations with their two carboxylic acid groups pointing to opposite directions in the solid state. Enantiomers of 3 form a step-like one-dimensional supramolecular polymer via intermolecular hydrogen bond interactions between the carboxylic acids for crystals obtained in methanol. No hydrogen bonds were formed between the carboxylic acids for crystals of 3 obtained in pyridine and aqueous guanidine solutions; instead, intermolecular hydrogen bonds between the carboxylic acid groups of 3 and pyridine, as well as guanidinium ions were formed. Under metal-mediated self-assembly conditions, the pyrazinyl nitrogen atoms in 3 interacted with transition metal ions, such as Ag(I), Cu(II) and Zn(II), and resulted in the formation of four new metal-containing supramolecular complexes. Metallomacrocycles 7, 8 and 9 were formed by reactions of 3 with Ag(I) or Cu(II) ions by bridging two ligands 3 in the equatorial region via M-N coordination bonds. A one-dimensional coordination polymer 10 was generated by reaction between ligand 3 and Zn(II) ions, and a cage-based structure is presented in 10 by bridging of the cyclophane units by Zn(2+) ions via Zn-N and Zn-O bonds.

The novel framework [{Co(en)2}2SbIII8VIV14O42(H2O)]·6H2O is composed of two-dimensional arrays of {SbIII8VIV14O42(H2O)} clusters interlinked via {Co(en)2} bridging groups; such antimony–vanadium clusters with antimony and vanadium in low oxidation states were previously unknown.

Under self-assembly conditions, the interaction between pyrimidinyl-containing oxacalixaromatics (1 and 2) and silver cation resulted in the formation of two-dimensional coordination networks 3 and 4; single crystal X-ray analysis revealed that complex 3 featured a coordination polymeric structure with ligand 1 arranged in an offset manner along the polymeric chain, while network 4 featured a structure with regular microcyclic channels.

A newly developed cinchonidine-derived phosphoramide 6b, simple and easily available, was identified as a powerful catalyst for the highly enantioselective Michael addition of both unprotected 3-aryl and 3-alkyloxindoles to β-substituted nitroalkenes to furnish the C3 quaternary stereogenic carbon center with an adjacent tertiary stereocenter in up to 21 : 1 diastereoselectivity and up to 99% enantioselectivity.

The reaction of oxacalix[2]benzene[2]pyrazines 1 and 2 with copper(II) nitrate, as well as dimeric copper(II) tetraacetate are presented. Ligands 1 and 2, both adopt 1,3-alternate conformation, with the two exo-Lewis basic sites spatially oriented outwards. Ligand 1 reacts with copper(II) ions generated a discrete molecular cage 3 by bridging two ligands via two Cu2+ ions in the equatorial region. While the reaction of 1 with dicopper(II) tetraacetate unit resulted in the formation of a discrete supramolecular complex 4 with 1:2 stoichiometry between the dicopper(II) unit and ligand 1, due to the larger size and axial coordination mode of the dicopper(II) unit. The conformationally flexible nature of ligand 2 facilitated the formation of coordination polymers 5 and 6 upon interaction with copper(II) and dicopper(II) units, respectively. Coordination polymer 5 featured a zigzag structure of alternating ligand 2 and Cu2+ ion, while in coordination polymer 6, ligand 2 serves as an axial 2-connected node, propagating the “paddlewheel” dicopper(II) unit along the polymeric chain.