Chun-Yi Sun

Chiral Nanoporous Metal‐Organic Frameworks with High Porosity as Materials for Drug Delivery

A chiral nanoporous metal-organic framework (MOF) with high porosity is obtained based on nontoxic zinc and achiral hexadentate ligand. It shows high drug loading and slow release of the proportion of the loaded drug with a complete delivery time of about one week when used as a material for adsorption and delivery of anticancer 5-fluorouracil.

Metal-organic frameworks as potential drug delivery systems

Introduction: Metal-organic frameworks (MOFs) are a unique class of hybrid porous solids based on metals and organic linkers. Compared to traditional porous materials, they possess predominance of large surface areas, tunable pore size and shape, adjustable composition and functionalized pore surface, which enable them unique advantages and promises for applications in adsorption and release of therapeutic agents. Areas covered: This review addresses MOFs as a new avenue for drug delivery and exhibits their ability to efficiently deliver various kinds of therapeutic agents. It also details the requirements that MOFs need to satisfy for biomedical application, such as toxicological compatibility, stability, particle size, and surface modification. In addition, several approaches used to enhance encapsulation efficiency are summarized and parameters influencing delivery efficiency are also discussed. Expert opinion: Benefiting from the unique advantages of MOFs materials, efficient delivery of various kinds of drugs has been achieved in some MOF materials. However, it is only the outset of MOFs in drug delivery system, and numerous work need to be done before clinical applications, for example, studying their in vivo toxicity, exploring degradation mechanisms so as to establish real stability of MOFs in bodys liquid, providing appropriated surface modification avenue for MOFs, and researching in vivo efficiency and pharmacokinetics of drug-loaded MOFs.

Controllable synthesis of isoreticular pillared-layer MOFs: gas adsorption, iodine sorption and sensing small molecules

Five isostructural pillared-layer MOFs (metal–organic frameworks) have been constructed by selection of layers and size-alterable pillar ligands. These MOFs show similar structures but different interlayer distances, pore volumes and pore surface functionalizations depending on the lengths and functions of pillar ligands. 1–5 display a certain degree of framework stabilities, and also exhibit CO2 uptakes. In addition, 1 can serve as a host for encapsulating I2 and exhibit an outstanding performance in reversible adsorption of iodine molecules. Furthermore, 1–5 can be used to separate dye molecules based on the size-exclusion effect and 3 can be employed as a column-chromatographic filler to separate Rhodamine B (RB) and Methylene Blue (MB).

Anion-directed genuine meso-helical supramolecular isomers of two 1D Ag(I) complexes based on arene-linked bis(pyrazolyl)methane ligands

Two genuine supramolecular isomers (Lp = p-[CH(pz)2]2C6H4), have been successfully obtained under similar solvothermal conditions by the reaction of arene-linked p-bis[bis(1-pyrazolyl)methyl]benzene ligand with AgNO3. Both of the compounds are made of unusual meso-helical chains and present a three-dimensional (3D) supramolecular structure. Compounds 1 and 2 were characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction and thermogravimetric (TG) analyses. The fluorescence property of them has also been studied.

Three cobalt(II)-linked {P8W48} network assemblies: syntheses, structures, and magnetic and photocatalysis properties.

Three cobalt(II)-containing tungstophosphate compounds, Na8Li8Co5[Co5.5(H2O)19P8W48.5O184]⋅60 H2O (1), K2Na4Li11Co5[Co7(H2O)28P8W48O184]Cl⋅ 59 H2O (2), and K2Na4LiCo11[Co8(H2O)32P8W48O184](CH3COO)4Cl⋅47 H2O (3), have been synthesized and characterized by IR spectroscopy, thermogravimetric analysis, elemental analyses, and magnetic measurements. The pH value impacts the formation of distinct cobalt-linked frameworks. The cyclic cavity of the polyanion accommodates 5.5, 7, and 8 cobalt ions in 1, 2, and 3, respectively. In compounds 1 and 2, each {Co5.5P8W48} and {Co7P8W48} fragment links to four others through multiple {Co-O-W} coordination bonds to generate a two-dimensional network. Compound 3 can be considered as a 3D network based on the {Co-O-W} coordination bonds and the {Co3(CH3COO)2(H2O)10} linkers between the {P8W48} fragments. Interestingly, acetate ligands have been employed to form the {Co3(CH3COO)2(H2O)10} unit, thereby inducing the construction of a 12-connected framework. To the best of our knowledge, compound 3 contains the largest-ever number of cobalt ions in a {P8W48}-based polyoxometalate when counterions are taken into account and the {P8W48} unit shows the highest number of connections thanks to the carboxyl bridges. The UV/Vis diffuse reflectance spectra of these powder samples indicate that the corresponding well-defined optical absorption associated with Eg can be assessed at 2.58, 2.48, and 2.73 eV and reveal the presence of an optical band gap. The photocatalytic H2 evolution activities of these {P8W48}-based compounds are evaluated.

Oxidative Polyoxometalates Modified Graphitic Carbon Nitride for Visible-Light CO2 Reduction

Developing a photocatalysis system for converting CO2 to valuable fuels or chemicals is a promising strategy to address global warming and fossil fuel consumption. Exploring photocatalysts with high-performance and low-cost has been two ultimate goals toward photoreduction of CO2. Herein, noble-metal-free polyoxometalates (Co4) with oxidative ability was first introduced into g-C3N4 resulted in inexpensive hybrid materials (Co4@g-C3N4) with staggered band alignment. The staggered composited materials show a higher activity of CO2 reduction than bare g-C3N4. An optimized Co4@g-C3N4 hybrid sample exhibited a high yield (107 μmol g-1 h-1) under visible-light irradiation (λ ≥ 420 nm), meanwhile maintaining high selectivity for CO production (94%). After 10 h of irradiation, the production of CO reached 896 μmol g-1. Mechanistic studies revealed the introduction of Co4 not only facilitate the charge transfer of g-C3N4 but greatly increased the surface catalytic oxidative ability. This work creatively combined g-C3N4 with oxidative polyoxometalates which provide novel insights into the design of low-cost photocatalytic materials for CO2 reduction.

New heteropolyniobates based on a bicapped Keggin-type {VNb14} cluster with selective adsorption and photocatalytic properties

New heteropolyniobates based on a bicapped Keggin-type {VNb14O42(NO3)2} (abbreviated as {VNb14}) cluster have been successfully synthesized by conventional aqueous methods. These clusters are a type of multifunctional material, which exhibit selective adsorption for methanol, ethanol and water and photocatalytic H2 evolution activity.

A hexanuclear cobalt metal–organic framework for efficient CO2 reduction under visible light

Increasing global challenges including climate warming and energy shortage have stimulated worldwide explorations for efficient materials for applications in the capture of CO2 and its conversion to chemicals. In this study, a novel pillared-layer porous metal–organic framework (Co6–MOF) with high nuclearity CoII clusters has been synthesized. This material exhibited a CO2 adsorption capacity of up to 55.24 cm3 g−1 and 38.17 cm3 g−1 at 273 K and 298 K, respectively. In a heterogeneous photocatalytic system of CO2 reduction, this material, co-operated with a ruthenium-based photosensitizer, can efficiently realize CO2 to CO conversion. Under visible-light irradiation for 3 hours, 39.36 μmol CO and 28.13 μmol H2 were obtained. This result is higher than those of most of the reported MOF materials under similar conditions and to the best of our knowledge, this is the first example of a high nuclear MOF used in CO2 reduction. The rooted reasons behind the high reactivity were studied through theoretical calculation studies. The results showed that electrons on reduced [Ru(bpy)3]Cl2·6H2O (bpy = 4,4′-bipyridine) could transfer to the Co6–MOF and the adsorbed CO2 molecule on the charged Co6–MOF could be activated more facilely. This work not only clarifies the reasons for high efficiency of the CO2 photoreduction system but also points out to us the direction for designing more effective MOF materials as photocatalysts for artificial CO2 photoreduction.

Graphene-coated hybrid electrocatalysts derived from bimetallic metal–organic frameworks for efficient hydrogen generation

In this study, we synthesized a low-cost electrocatalyst, Ni/Mo2C nanoparticles coated with graphene shells (denoted as NiMo2C@C), via a facile carburization process of porous bimetallic metal–organic frameworks (NiMo-MOF). This is the first example of a Ni and Mo2C nanocomposite derived from a bimetallic MOF that demonstrates excellent electrocatalytic activity and remarkable durability as long as 10 h under acidic and basic conditions. The overpotentials are 169 mV and 181 mV to reach the current density of 10 mA cm−2, respectively. The favorable performance can be ascribed to the synergistic effect between Mo2C and Ni as well as the homogeneous distribution, graphene coating and mesoporous structure which is in favor of the charge transfer in the HER. This work may provide some guidelines for fabricating nanostructured hybrids composed of versatile transition metal carbides and graphene with high performance and stability in different media based on designed MOFs.

A new organic-inorganic hybrid based on the crescent-shaped polyoxoanion [H6SiNb18O54]8- and copper-organic cations.

A new organic-inorganic hybrid, [Cu(en)(2)](3){[Cu(en)(2)][H(6)SiNb(18)O(54)]}·22H(2)O (1, en = ethylenediamine) containing the crescent-shaped polyoxoanion [H(6)SiNb(18)O(54)](8-) and copper-organic cations has been successfully synthesized, and elemental analyses, IR spectra, thermogravimetric analyses and single-crystal X-ray diffraction were investigated.