Long-Range π-π Stacking Brings High Electron Delocalization for Enhanced Photocatalytic Activity in Hydrogen-Bonded Organic Framework.

Unlike many studies that regulate transport and separation behaviour of photogenerated charge carriers through controlling the chemical composite, our work demonstrates this goal can be achieved through simply tuning the molecular π-π packing from short-range to long-range within hydrogen-bonded organic frameworks (HOFs) without altering the building blocks or network topology. Further investigations reveal that the long-range π-π stacking significantly promotes electron delocalization and enhances electron density, thereby effectively suppressing electron-hole recombination and augmenting the charge transfer rate. Simultaneously, acting as a porous substrate, it boosts electron density of Pd nanoparticle loaded on its surfaces, resulting in remarkable CO photoreduction catalytic activity (CO generation rate: 48.

Anchoring Single-Atomic Metal Sites in Metalloporphyrin-Based Covalent Organic Frameworks for Enhanced Photocatalytic Hydrogen Evolution.

A photoactive covalent organic framework (COF) was built from metalloporphyrin and bipyridine monomers and single-atomic Pt sites were subsequently installed. Integrating photosensitizing metalloporphyrin and substrate-activating Pt(bpy) moieties in a single solid facilitates multielectron transfer and accelerates photocatalytic hydrogen evolution with a maximum production rate of 80.4 mmol h g and turnover frequency (TOF) of 15.

Exfoliation of a Two-Dimensional Metal-Organic Framework for Enhanced Photocatalytic CO Reduction.

A two-dimensional metal-organic framework, FICN-12, was constructed from tris[4-(1-pyrazole-4-yl)phenyl]amine (HTPPA) ligands and Ni secondary building units. The triphenylamine moiety in the HTPPA ligand readily absorbs UV-visible photons and sensitizes the Ni center to drive photocatalytic CO reduction. FICN-12 can be exfoliated into monolayer and few-layer nanosheets with a "top-down" approach, which exposes more catalytic sites and increases its catalytic activity.

Modulating the Schottky barrier of Pt/PbTiO for efficient piezo-photocatalytic hydrogen evolution.

Charge recombination severely restricts the photocatalytic efficiencies of materials. Loading cocatalysts on the surface of host photocatalysts is a promising strategy for charge separation, which, however, suffers from the large Schottky barrier at the cocatalyst/host interface. Herein, a series of Pt/PbTiO compounds were constructed as a proof-of-concept utilizing the piezoelectric field of PbTiO under acoustic vibrations to modulate the height of the interfacial Schottky barrier.

Facile Preparation of Hydrogen-Bonded Organic Framework/CuO Heterostructure Films via Electrophoretic Deposition for Efficient CO Photoreduction.

Photocatalytic CO reduction is one of the most cost-effective and environmentally friendly techniques of converting CO into high-value compounds and/or fuels. However, the performance of most current photocatalytic CO reduction catalysts is less than satisfactory for practical applications. Here, we synthesized a heterogeneous structure by integrating CuO and a porphyrin hydrogen-bonded organic framework (PFC-45), which was then fabricated into a thin-film catalyst on carbolic paper (CP) using a facile electrophoretic deposition technology.

Partial Metalation of Porphyrin Moieties in Hydrogen-Bonded Organic Frameworks Provides Enhanced CO Photoreduction Activity.

In natural photosynthesis, the architecture of multiproteins integrates more chromophores than redox centers and simultaneously creates a well-controlled environment around the active site. Herein, we demonstrate that these features can be emulated in a prototype hydrogen-bonded organic framework (HOF) through simply varying the proportion of metalated porphyrin in the structure. Further studies demonstrate that changing the metalloporphyrin content not only realizes a fine tuning of the photosensitizer/catalyst ratio, but also alters the microenvironment surrounding the active site and the charge separation efficiency.

Engineering Hierarchical Architecture of Metal-Organic Frameworks for Highly Efficient Overall CO Photoreduction.

Previous studies on syntheses of metal-organic frameworks (MOFs) for photocatalytic CO reduction are mainly focused on the exquisite control over the net topology and the functionality of metal clusters/organic building blocks. This contribution demonstrates that the rational design of MOF-based photocatalyst can be further extended to the hierarchical structure at micrometer scales well beyond the conventional MOF design at the molecular level. By taking advantage of the disparity of two selective MOFs in nucleation kinetics, a hierarchical core-shell MOF@MOF structure is successfully constructed through a simple one-pot synthesis.

Metallization-Prompted Robust Porphyrin-Based Hydrogen-Bonded Organic Frameworks for Photocatalytic CO Reduction.

Under topological guidance, the self-assembly process based on a tetratopic porphyrin synthon results in a hydrogen-bonded organic framework (HOF) with the predicted square layers topology (sql) but unsatisfied stability. Strikingly, simply introducing a transition metal in the porphyrin center does not change the network topology but drastically causes noticeable change on noncovalent interaction, orbital overlap, and molecular geometry, therefore ultimately giving rise to a series of metalloporphyrinic HOFs with high surface area, and excellent stability (intact after being soaked in boiling water, concentrated HCl, and heated to 270 °C). On integrating both photosensitizers and catalytic sites into robust backbones, this series of HOFs can effectively catalyze the photoreduction of CO to CO, and their catalytic performances greatly depend on the chelated metal species in the porphyrin centers.

Radiochromic Hydrogen-Bonded Organic Frameworks for X-ray Detection.

Porous materials have been investigated as efficient photochromic platforms for detecting hazardous radiation, while the utilization of hydrogen bonded organic frameworks (HOFs) in this field has remained intact. Herein, two HOFs were synthesized through self-assembly of tetratopic viologen ligand and formic acid (PFC-25, PFC-26), as a new class of "all-organic" radiochromic smart material, opening a gate for HOFs in this field. PFC-26 is active upon both X-ray and UV irradiation, while PFC-25 is only active upon X-ray irradiation.

Boosting Interfacial Charge-Transfer Kinetics for Efficient Overall CO Photoreduction via Rational Design of Coordination Spheres on Metal-Organic Frameworks.

The recombination of electron-hole pairs severely detracts from the efficiency of photocatalysts. This issue could be addressed in metal-organic frameworks (MOFs) through optimization of the charge-transfer kinetics via rational design of structures at atomic level. Herein, a pyrazolyl porphyrinic Ni-MOF (PCN-601), integrating light harvesters, active catalytic sites, and high surface areas, has been demonstrated as a superior and durable photocatalyst for visible-light-driven overall CO reduction with HO vapor at room temperature.

An easy and low-cost method of embedding chiral molecules in metal-organic frameworks for enantioseparation.

A facile method, post-synthetic exchange of modulators (PSEm), has been demonstrated here to prepare chiral metal-organic frameworks for enantioseparation. Based on this method, three chiral porous Zr-based metal-organic frameworks have been prepared through exchanging the coordinated modulators on metal clusters of MOFs with commercially available chiral carboxylic acid molecules. In addition, the obtained materials show enantioselectivity toward three different enantiomers, which presents a proof of concept for the design of MOF materials for enantioseparation by an easy and low-cost method.

Record Complexity in the Polycatenation of Three Porous Hydrogen-Bonded Organic Frameworks with Stepwise Adsorption Behaviors.

Hydrogen-bonded organic frameworks (HOFs) show great potential in many applications, but few structure-property correlations have been explored in this field. In this work, we report that self-assembly of a rigid and planar ligand gives rise to flat hexagonal honeycomb motifs which are extended into undulated two-dimensional (2D) layers and finally generate three polycatenated HOFs with record complexity. This kind of undulation is absent in the 2D layers built from a very similar but nonplanar ligand, indicating that a slight torsion of ligand produces overwhelming structural change.

A Comparison of Two Isoreticular Metal-Organic Frameworks with Cationic and Neutral Skeletons: Stability, Mechanism, and Catalytic Activity.

Although many ionic metal-organic frameworks (MOFs) have been reported, little is known about how the charge of the skeleton affects the properties of the MOF materials. Herein we report how the chemical stability of MOFs can be substantially improved through embedding electrostatic interactions in structure. A MOF with a cationic skeleton is impervious to extremely acidic, oxidative, reductive, and high ionic strength conditions, such as 12 m HCl (301 days), aqua regia (86 days), H O (30 days), and seawater (30 days), which is unprecedented for MOFs.

Study on water splitting characteristics of CdS nanosheets driven by the coupling effect between photocatalysis and piezoelectricity.

Ultrathin semiconductors have been proposed as an excellent platform to promote solar conversion due to their ultra-large specific surface area and unique surface structures. So far, the researchers designed and constructed some multi-component heterostructure photocatalysts, but they are still unable to avoid the recombination of photoexcited electron-hole pairs. This study introduces a built-in electric field in a one-component nanosheet to promote photo-generated carrier separation.

Sensing HIV related protein using epitope imprinted hydrophilic polymer coated quartz crystal microbalance.

We have developed a biomimetic sensor for the detection of human immunodeficiency virus type 1 (HIV-1) related protein (glycoprotein 41, gp41) based on epitope imprinting technique. gp41 is the transmembrane protein of HIV-1 and plays an important role in membrane fusion between viruses and infected cells. It is an important index for determining the extent of HIV-1 disease progression and the efficacy of therapeutic intervention.