Strong Second-Harmonic Generation Induced by a Triphenylamine-Based Bismuth-Organic Framework for Photocatalytic Activity Enhancement.

Taking advantage of the well-defined geometry of metal centers and highly directional metal-ligand coordination bonds, metal-organic frameworks (MOFs) have emerged as promising candidates for nonlinear optical (NLO) materials. In this work, taking a photoresponsive carboxylate triphenylamine derivative as an organic ligand, a bismuth-based MOF, Bi-NBC, NBC = 4',4‴,4‴″-nitrilotris(([1,1'-biphenyl]-4-carboxylic acid)) is obtained. Structure determination reveals that it is a potential NLO material derived from its noncentrosymmetric structure, which is finally confirmed by its rarely strong second harmonic generation (SHG) effect. Theoretical calculations reveal that the potential difference around Bi atoms is large; therefore, it leads to a strong local built-in electric field, which greatly facilitates the charge separation and transfer and finally improves the photocatalytic performance. Our results provide a reference for the exploration of MOFs with NLO properties.

Extended Light Absorption and Improved Charge Separation by Protonation of the Organic Ligand in a Bismuth-Based Metal-Organic Framework.

In this work, a new method to extend the light absorption and improve the photocatalytic activity of metal-organic frameworks (MOFs) with nitrogen-containing ligand is reported, namely, the protonation of nitrogen. Specifically, a protonated Bi-based MOF synthesized by a hydrothermal method (Bi-MMTAA-H, MMTAA=2-mercapto-4-methyl-5-thiazoleacetic acid) displays a wider visible light absorption than Bi-MMTAA-R with the same single-crystal structure, but synthesized by a reflux method. The redshifted light absorption was confirmed to be caused by the protonation of nitrogen in the thiazolyl ring in MMTAA. Moreover, this protonation also facilitates the charge separation and transfer and improves the photocatalytic activity of selective oxidation of α-terpinene to p-cymene. Our results provide a new idea for nitrogen-containing Bi-based MOFs to extend the light absorption and improve the photocatalytic performance.

Corrigendum to "Influence of interaction between organic cation and inorganic unit in bi-based hybrid perovskites for photoelectronic properties" < [Heliyon Volume 8, Issue 12, December 2022, Article e12528]>.

[This corrects the article DOI: 10.1016/j.heliyon.2022.e12528.].

A Bismuth-Based Metal-Organic Framework for Visible-Light-Driven Photocatalytic Decolorization of Dyes and Oxidation of Phenylboronic Acids.

In this work, a Bi-based metal-organic framework (MOF; Bi-MMTAA) with 2-mercapto-4-methyl-5-thiazoleacetic acid (MMTAA) as the organic ligand is synthesized. The crystal structure of Bi-MMTAA was determined by single-crystal X-ray diffraction. Theoretical calculations reveal that Bi-MMTAA is a p-type semiconductor, and electrons can delocalize through the π-conjugation when excited by a photon with an energy higher than the Bi-MMTAA band gap, which is beneficial to charge separation and transfer. The photoelectrical properties suggest that free electrons can be produced over Bi-MMTAA under light irradiation. The photocatalytic results suggest that Bi-MMTAA can decolorize rhodamine B (RhB) and oxidize phenylboronic acid to phenol under visible light (λ > 420 nm), with superoxide radicals being the main reactive oxygen species. Our results enrich the family of Bi-based MOFs and may inspire further exploration of Bi-based MOFs, including both synthesis and potential applications.

Photo-induced photo-thermal synergy effect leading to efficient CO2 cycloaddition with epoxide over a Fe-based metal organic framework.

It is crucial to design and synthesize a catalyst that can catalyze the production of cyclic carbonates from CO2 and epoxide under mild conditions. Herein, we successfully synthesized a two-dimensional metal organic framework FeTPyP, which displays an outstanding capability to catalyze the CO2 cycloaddition reaction under light irradiation with a yield of styrene carbonate as high as 106.13 mmol/(g h). Characterizations suggests that the major reason is due to (1) the synergistic effect between photocatalysis and thermocatalysis and (2) ultraviolet light can promote the ring-opening reaction of styrene oxide. This work provides an alternative approach to further design efficient heterogeneous catalysts for photo-induced CO2 cycloaddition reaction via coupling thermocatalysis and photocatalysis.

Enhanced photocatalytic driven hydroxylation of phenylboric acid to phenol over pyrenetetrasulfonic acid intercalated ZnAl-LDHs.

Layered double hydroxides (LDHs) own admirable potential due to their controllable composition and exchangeable interlayer anions. Herein, pyrenetetrasulfonic acid (PTS) intercalated ZnAl-LDHs (denoted as ZnAl-xPTS, x represents the amount of NaPTS in the starting material) are synthesized by a co-precipitation method, which display enhanced photocatalytic activity towards the hydroxylation of phenylboric acid to phenol. Various characterizations suggest that PTS plays significant roles in improving the photocatalytic activity: (1) PTS extends the light absorption from ultraviolet to visible light region; (2) the introduction of PTS upshifts the conduction band, which is feasible for the formation of O2∙-; (3) ZnAl-xPTS produces more free electrons under light irradiation, which leads to greatly improved activity. This study develops an alternative LDHs based photocatalyst for the production of phenol, which also provides an efficient strategy to improve the photocatalytic activity of LDHs.

Influence of interaction between organic cation and inorganic unit in bi-based hybrid perovskites for photoelectronic properties.

With the increase of the passion on lead-free perovskites, more and more endeavor focused on halobismuthates. Here, we have introduced the p-iodoaniline and p-phenylenediamine into Bi-based hybrid materials, and two photoactive iodobismuthate named p-phenylenediamine iodobismuthate (PDABI) and p-iodoaniline iodobismuthate (PIDBI) were prepared. Their single structures, band gaps, thermostability and other properties were explored. The structure results revealed that they all have 1D BiI4 - anion chains with edge-shared BiI6 octahedron. The DFT result revealed that PIDBI had an inherent interaction between the I substituent in p-iodoaniline cation and the Bi atom in inorganic BiI4 - anion chains. The photodetector assembled by PDABI and PIDBI revealed that the interaction provided by symmetric p-phenylenediamine has a positive effect on PIDBI's optoelectronic properties compared to the role of asymmetric p-iodoaniline in PDABI.

Tuning the Conduction Band Potential of Bi-based Semiconductors Using a Combination of Organic Ligands.

Most Bi-based semiconductors are incapable of photocatalytic reduction reaction from a thermodynamic view, owing to relatively positive conduction band potentials (ECB ). Here, a novel Bi-based metal-organic framework (Bi-MBA, MBA=4-mercaptobenzoic acid) with excellent photocatalytic reduction activities is developed. The ECB of Bi-MBA locates at -1.38 eV, which is able to efficiently reduce O2 , CrVI and CO2 . Theoretical calculations reveal the significant contribution of organic ligand (MBA) to the conduction band. Our results provide an effective route to improve the photocatalytic reduction activities of Bi-based photocatalysts.

Photostable Ag(I)-Based Metal-Organic Framework: Synthesis, Structure, and Photocatalytic Selective Oxidation Properties.

For Ag(I)-based photocatalysts, the photoreduction of Ag+ to metallic Ag is an unignorable issue, which is the major reason for their instability. If electrically neutral excitons rather than electrons were produced over Ag(I)-based photocatalysts, the photoreduction of Ag+ is expected to be greatly suppressed. To check this assumption, a Ag-based metal-organic framework containing pyrene, which is in favor of exciton production, is synthesized (denoted as Ag-PTS-BPY) and the structure is solved via single-crystal X-ray diffraction. Ag-PTS-BPY is applied in the photocatalytic selective oxidation of methyl phenyl sulfide, which displays high conversion and selectivity. As expected, no metallic Ag is formed after five cycles of reaction according to the results of X-ray diffraction, Fourier transform infrared, and X-ray photoelectron spectroscopy, and the high conversion is also maintained. The participation of excitons suppresses the involvement of electrons, which are believed to be the reason for the high stability of Ag-PTS-BPY.

Fluorescent hollow mesoporous carbon spheres for drug loading and tumor treatment through 980-nm laser and microwave co-irradiation.

Hollow mesoporous particles for drug delivery and cancer therapy have attracted significant attention over recent decades. Here, we develop a simple and highly efficient strategy for preparing fluorescent hollow mesoporous carbon spheres (HMCSs). Compared with typical carbon materials such as fullerene C60, carbon nanotubes, reduced graphene oxide, and carbon nanohorns; HMCSs showed fewer effects on cell cycle distribution and lower toxicity to cells. Ten different drugs were incorporated into the HMCSs, and the maximum loading efficiency reached 42.79 ± 2.7%. Importantly, microwaves were found to improve the photothermal effect generated by HMCSs when combined with 980-nm laser irradiation. The cell killing and tumor growth inhibition efficiencies of HMCSs and drug-loaded HMCSs under co-irradiation with laser and microwaves were significantly improved compared with those under laser irradiation alone. After local administration HMCSs were only distributed in tissue at the injection site. HMCSs showed almost no toxicity in mice after local injection and could be completely removed from the injection site.