Fluorination and Conjugation Engineering Synergistically Enhance the Optoelectronic Properties of Two-Dimensional Hybrid Organic–Inorganic Perovskites

Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) are expected to be a viable alternative to three-dimensional (3D) analogs in solar cells (SCs) and optoelectronic devices due to their high stability, diverse composition, and physical properties. However, unsuitable band alignment and large bandgaps limit the power conversion efficiency (PCE) improvement of SCs based on 2D HOIPs. Here, we report a molecular design strategy that combines fluorination and conjugation engineering to tune the electronic structure and optimize the PCE of 2D HOIPs. Our results show that type IIa band alignment and tunable bandgaps can be achieved in 2D Dion–Jacobson (DJ) HOIPs by H/F substitution of organic cations with different degrees of conjugation. In general, the bandgap of 2D DJ-HOIPs decreases monotonously with the increase of the number of F atoms, which is due to the gradual decrease of the lowest unoccupied molecular orbitals (LUMO) of organic cations. In addition, the enhanced interlayer charge transfer and higher dielectric constant suggest that the fluorination-induced dielectric limitations are weakened. The estimated PCE of 2D DJ-HOIPs is exponentially increased and positively correlated with the degree of conjugation and fluorination of organic cations, with a PCE approaching 29% under their synergistic effect. Our results not only provide promising candidates for photovoltaic device applications but also provide an effective method for PCE optimization

Fluorination and Conjugation Engineering Synergistically Enhance the Optoelectronic Properties of Two-Dimensional Hybrid Organic–Inorganic Perovskites

Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) are expected to be a viable alternative to three-dimensional (3D) analogs in solar cells (SCs) and optoelectronic devices due to their high stability, diverse composition, and physical properties. However, unsuitable band alignment and large bandgaps limit the power conversion efficiency (PCE) improvement of SCs based on 2D HOIPs. Here, we report a molecular design strategy that combines fluorination and conjugation engineering to tune the electronic structure and optimize the PCE of 2D HOIPs. Our results show that type IIa band alignment and tunable bandgaps can be achieved in 2D Dion–Jacobson (DJ) HOIPs by H/F substitution of organic cations with different degrees of conjugation. In general, the bandgap of 2D DJ-HOIPs decreases monotonously with the increase of the number of F atoms, which is due to the gradual decrease of the lowest unoccupied molecular orbitals (LUMO) of organic cations. In addition, the enhanced interlayer charge transfer and higher dielectric constant suggest that the fluorination-induced dielectric limitations are weakened. The estimated PCE of 2D DJ-HOIPs is exponentially increased and positively correlated with the degree of conjugation and fluorination of organic cations, with a PCE approaching 29% under their synergistic effect. Our results not only provide promising candidates for photovoltaic device applications but also provide an effective method for PCE optimization

Selective Co(II) Adsorption Using Hollow ZIF‑8 Nanostructures with Embedded Fe₃O₄ Nanoparticles

In this study, we developed a magnetic hollow metal–organic framework (Fe3O4/HZIF-8) nanocomposite by modifying ZIF-8 nanocrystals with magnetic Fe3O4 nanoparticles at room temperature. The resulting Fe3O4/HZIF-8 nanostructured composite was used as an absorbent for Co(II) elimination. Due to the functionalization of Fe3O4 nanoparticles and the hollow structure of ZIF-8, the prepared absorbent showed a maximum adsorption capacity of 155.8 mg g–1 within 4 h and could be easily separated from the matrix using magnetization. Additionally, the absorbent exhibited a wide pH tolerance range from pH 2.0 to 9.0 and maintained excellent selectivity for Co(II) adsorption in simulated wastewater. The experimental data was well described by the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model. The ultraviolet–visible spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) studies further indicated that complexation reactions dominated the adsorption of Co(II). Thereby, the nanostructured hollow MOF could be performed as a high-performance absorbent for pollutant removal. This work sheds light on the nanostructured design and uptake mechanism study of the metal ions and radionuclide removal

Fabrication of Slippery Lubricant-Infused Porous Surface for Inhibition of Microbially Influenced Corrosion

Microbially influenced corrosion (MIC) accelerates the failure of metal in a marine environment. In this research, slippery lubricant-infused porous surface (SLIPS) was designed on aluminum, and its great potential for inhibiting MIC induced by sulfate-reducing bacteria (SRB) was demonstrated in a simulated marine environment. The inhibition mechanism of SLIPS to MIC was proposed based on its effective roles in the suppression of SRB settlement and isolation effect to corrosive metabolites. The liquid-like property is demonstrated to be the major contributor to the suppression effect of SLIPS to SRB settlement. The effects of environmental factors (static and dynamic conditions) and lubricant type to SRB settlement over SLIPS were also investigated. It was indicated that the as-fabricated SLIPS can inhibit the SRB settlement in both static and dynamic marine conditions, and lubricant type presents a negligible effect on the SRB settlement. These results will provide a series of foundational data for the future practical application of SLIPS in the marine environment, and also a lubricant selecting instruction to construct SLIPS for MIC control

In Situ Measurement of the Supramolecular Chirality in the Langmuir Monolayers of Achiral Porphyrins at the Air/Aqueous Interface by Second Harmonic Generation Linear Dichroism

Chiral porphyrin assemblies are promising molecular materials because they possess unique biological compatibility and excellent electronic properties. Metal ions can strongly affect the formation of supramolecular chirality. In this paper, we investigated the effect of metal ions in the subphase on the supramolecular chirality of a porphyrin derivative with two long hydrophobic chains (TPPA2a) at the air/aqueous interfaces by means of second harmonic generation linear dichroism (SHG-LD). It was found that TPPA2a can form chiral assemblies at the air/aqueous interface even though the molecule itself is achiral. Furthermore, metal ions added into the subphase have a considerable effect on the interfacial supramolecular chirality: Zn²⁺ inhibits the formation of supramolecular chirality, while Cu²⁺ promotes the formation. We suggest that the effect of metal ions on the supramolecular chirality is due to the coordination between the metal ions and TPPA2a molecules. To clarify the coordination mechanism, we also performed UV–vis measurements of TPPA2a Langmuir–Blodgett (LB) films and SHG-LD experiments on TPPA4, which is similar to TPPA2a but without ester groups. These results revealed that the metal ions did not interact with the central nitrogen of porphyrin rings, while the coordination between metal ions and the ester groups possibly affects the supramolecular chirality. This is a novel mechanism involving coordination between metal cations and side chains of porphyrin derivatives, and it may provide a deeper understanding of the supramolecular chirality of porphyrin assemblies

Two-Photon-Induced Isomerization of Spiropyran/Merocyanine at the Air/Water Interface Probed by Second Harmonic Generation

Photochromic molecules often exhibit switchable hyperpolarizabilities upon photoisomerization between two molecular states and can be widely applied in nonlinear optical materials. Photoisomerization can occur through either one-photon or two-photon processes. Two-photon-induced isomerization has several advantages over one-photon process but has not been fully explored. In the present study, we have used second harmonic generation to investigate the two-photon-induced isomerization between spiropyran and merocyanine at the air/water interface. We show that spiropyran and merocyanine can be converted into each other reversibly with 780-nm laser-beam irradiation through two-photon processes. We also investigated the isomerization rates under various incident laser powers. Quantitative analysis revealed that the isomerization rates of spiropyran and merocyanine depend differently on the laser power. We attribute the difference to the distinct molecular structures of spiropyran and merocyanine. At the interface, nonplanar spiropyran molecules exist mainly as monomers, whereas planar merocyanine molecules form aggregates. Upon aggregation, steric hindrance effects and excitonic coupling efficiently arrest the photoisomerization of merocyanine. This work provides an in-depth understanding of two-photon-induced isomerization at the interface, which is beneficial for designing and controlling optical thin-film materials

Two new entangled complexes based on 4,4′-bis(1-imidazolyl)biphenyl: syntheses, structures, thermal and photoluminescent properties

<div><p>Two new entangled complexes, [Zn(bibp)(L¹)]·0.25H₂O (<b>1</b>) and [Co(bibp)(H₂L²)] (<b>2</b>) (bib<i>p</i> = 4,4′-bis(1-imidazolyl)biphenyl, H₂L¹ = 4,4′-(2,2′-oxybis(ethane-2,1-diyl)bis(oxy))dibenzoic acid, and H₄L² = 5,5′-(2,2′-oxybis(ethane-2,1-diyl)bis(oxy))diisophthalic acid), have been synthesized hydrothermally. Complex <b>1</b> features a new uninodal four-connected (6⁵·8) net with vertex symbol 6·6·6·6·6₂·8₂, which is different from all that exhibit uninodal four-connected (6⁵·8) nets found in the literature, including <b>cds</b>, <b>dmp</b>, <b>ict</b>, <b>mok</b>, <b>unl</b> and <b>unm</b>. Three of these nets interpenetrate. Complex <b>2</b> shows an unusual threefold 2-D → 3-D polythreaded framework, in which each 2-D wave-like net is formed by the intersection, at the shared Co nodes, of the 1-D left- and right-handed single-helical (H₂L²)²⁻ chains and the 1-D bibp <i>meso</i>-helices. Furthermore, the thermal and photoluminescent properties of <b>1</b> have also been studied.</p></div

Successive Adsorption of Cations and Anions of Water–1-Butyl-3-methylimidazolium Methylsulfate Binary Mixtures at the Air–Liquid Interface Studied by Sum Frequency Generation Vibrational Spectroscopy and Surface Tension Measurements

We have investigated the surface behavior of 1-butyl-3-methyl­imidazolium methylsulfate ([bmim]­[MS]) aqueous solutions by sum frequency generation vibrational spectroscopy (SFG-VS) and surface tension measurements, including the adsorption of ions and its relationship with surface tension. At very low [bmim]­[MS] concentrations, SFG-VS data indicate that with increasing mole fraction of [bmim]­[MS], adsorption of cations at the interface rapidly increases, whereas the surface tension rapidly decreases. When cation adsorption to the surface is close to saturation, the change of the surface tension tends to be gradual. When the mole fraction of [bmim]­[MS] reaches 0.1, anions begin to adsorb to the interface, leading to the changes of the orientation angle of cations and the aggregation behavior of cations and anions at the interface. The previously reported unusual minimum point in the surface tension curve of [bmim]­[BF₄] aqueous solution suggested to be caused by successive adsorption of cations and anions was not observed for [bmim]­[MS] aqueous solution. SFG-VS spectra and the surface tension curve of [bmim]­[MS] aqueous solution indicate that anion adsorption does not significantly affect the surface tension. These results provide important information about the surface behavior of ionic liquid aqueous solutions and the effect of adsorption of ions on the surface tension

Photodimerization Kinetics of a Styrylquinoline Derivative in Langmuir–Blodgett Monolayers Monitored by Second Harmonic Generation

To explore the influence of surface packing densities on the interfacial photochemical kinetics, the surface-selective second harmonic generation (SHG) technique was used to investigate the kinetics of two-photon induced [2 + 2] photocycloadditions of a styrylquinoline alkoxy derivative within the Langmuir–Blodgett (LB) monolayers. The laser power dependence experiment revealed that this interfacial photodimerization is a first-order reaction, which implies that the photoexcitation is the rate-limiting step. Interestingly, a comparison of photodimerization kinetics at different surface packing densities shows a nonmonotonic distribution of reaction rate constants, which can be attributed to a result of combined effects of the topochemical mechanism and steric hindrance. The atomic force microscopy measurements and theoretical calculations were also employed to help understand the [2 + 2] photocycloaddition mechanisms. The results presented in this work demonstrate that the surface packing density plays an important role in regulating the interfacial photoreactions within the LB monolayers composed of the conjugated aromatic molecular systems

Development of In Silico Models for Predicting Potential Time-Dependent Inhibitors of Cytochrome P450 3A4

Cytochrome P450 3A4 (CYP3A4) is one of the major drug metabolizing enzymes in the human body and metabolizes ∼30–50% of clinically used drugs. Inhibition of CYP3A4 must always be considered in the development of new drugs. Time-dependent inhibition (TDI) is an important P450 inhibition type that could cause undesired drug–drug interactions. Therefore, identification of CYP3A4 TDI by a rapid convenient way is of great importance to any new drug discovery effort. Here, we report the development of in silico classification models for prediction of potential CYP3A4 time-dependent inhibitors. On the basis of the CYP3A4 TDI data set that we manually collected from literature and databases, both conventional machine learning and deep learning models were constructed. The comparisons of different sampling strategies, molecular representations, and machine-learning algorithms showed the benefits of a balanced data set and the deep-learning model featured by GraphConv. The generalization ability of the best model was tested by screening an external data set, and the prediction results were validated by biological experiments. In addition, several structural alerts that are relevant to CYP3A4 time-dependent inhibitors were identified via information gain and frequency analysis. We anticipate that our effort would be useful for identification of potential CYP3A4 time-dependent inhibitors in drug discovery and design