Large Mid-IR Second-Order Nonlinear-Optical Effects Designed by the Supramolecular Assembly of Different Bond Types without IR Absorption

Two new different-bond-type hybrid compounds, (Hg₆P₄Cl₃)­(PbCl₃) (<b>1</b>) and (Hg₂₃P₁₂)­(ZnCl₄)₆ (<b>2</b>), with supramolecular interactions between host and guest moieties, which based on metal–pnicogen, pnicogen–pnicogen, and metal–halogen bonds were obtained by solid-state reactions. Compounds <b>1</b> and <b>2</b> show large second-harmonic-generation (SHG) activity and are transparent in the wide mid-IR region, providing an effective route for searching new IR nonlinear-optical material systems by combining two or more different bond types with no IR absorption within a single compound through supramolecular assembly. Theory predications based on first-principles calculations are also performed on the SHG properties of <b>1</b> and <b>2</b>

Large Mid-IR Second-Order Nonlinear-Optical Effects Designed by the Supramolecular Assembly of Different Bond Types without IR Absorption

Two new different-bond-type hybrid compounds, (Hg₆P₄Cl₃)­(PbCl₃) (<b>1</b>) and (Hg₂₃P₁₂)­(ZnCl₄)₆ (<b>2</b>), with supramolecular interactions between host and guest moieties, which based on metal–pnicogen, pnicogen–pnicogen, and metal–halogen bonds were obtained by solid-state reactions. Compounds <b>1</b> and <b>2</b> show large second-harmonic-generation (SHG) activity and are transparent in the wide mid-IR region, providing an effective route for searching new IR nonlinear-optical material systems by combining two or more different bond types with no IR absorption within a single compound through supramolecular assembly. Theory predications based on first-principles calculations are also performed on the SHG properties of <b>1</b> and <b>2</b>

Photochromic Metal Complexes of <i>N</i>-Methyl-4,4′-Bipyridinium: Mechanism and Influence of Halogen Atoms

Photochromism of <i>N</i>-methyl-4,4′-bipyridinium (MQ⁺) salts and their metal complexes has never been reported. A series of MQ⁺ coordinated halozinc complexes [(MQ)­ZnX₃] (X = Cl (<b>1</b>), Br (<b>2</b>), I (<b>3</b>)) and [(MQ)­ZnCl_1.53I_1.47]₂(MQ)­ZnCl_1.68I_1.32 (<b>4</b>), with better physicochemical stability than halide salts of the MQ⁺ cation, have been found to exhibit different photochromic behaviors. Compounds <b>1</b>–<b>3</b> are isostructural, but only <b>1</b> and <b>2</b> show photochromism. Introduction of partial Cl atoms to nonphotochromic compound <b>3</b> yields compound <b>4</b>, which also displays photochromism. The photochromic response of <b>1</b>, <b>2</b>, and <b>4</b> indicates the presence of their long-lived charge separation states, which originate from X → MQ⁺ electron transfer according to ESR and XPS measurements. Studies on the influence of different coordinated halogen atoms demonstrate that the Cl atom may be a more suitable electron donor than Br and I atoms to design redox photochromic metal complexes

Photochromic Metal Complexes of <i>N</i>-Methyl-4,4′-Bipyridinium: Mechanism and Influence of Halogen Atoms

Photochromism of <i>N</i>-methyl-4,4′-bipyridinium (MQ⁺) salts and their metal complexes has never been reported. A series of MQ⁺ coordinated halozinc complexes [(MQ)­ZnX₃] (X = Cl (<b>1</b>), Br (<b>2</b>), I (<b>3</b>)) and [(MQ)­ZnCl_1.53I_1.47]₂(MQ)­ZnCl_1.68I_1.32 (<b>4</b>), with better physicochemical stability than halide salts of the MQ⁺ cation, have been found to exhibit different photochromic behaviors. Compounds <b>1</b>–<b>3</b> are isostructural, but only <b>1</b> and <b>2</b> show photochromism. Introduction of partial Cl atoms to nonphotochromic compound <b>3</b> yields compound <b>4</b>, which also displays photochromism. The photochromic response of <b>1</b>, <b>2</b>, and <b>4</b> indicates the presence of their long-lived charge separation states, which originate from X → MQ⁺ electron transfer according to ESR and XPS measurements. Studies on the influence of different coordinated halogen atoms demonstrate that the Cl atom may be a more suitable electron donor than Br and I atoms to design redox photochromic metal complexes

Design Strategy for Improving Optical and Electrical Properties and Stability of Lead-Halide Semiconductors

Broad absorption, long-lived photogenerated carriers, high conductance, and high stability are all required for a light absorber toward its real application on solar cells. Inorganic–organic hybrid lead-halide materials have shown tremendous potential for applications in solar cells. This work offers a new design strategy to improve the absorption range, conductance, photoconductance, and stability of these materials. We synthesized a new photochromic lead-chloride semiconductor by incorporating a photoactive viologen zwitterion into a lead-chloride system in the coordinating mode. This semiconductor has a novel inorganic–organic hybrid structure, where 1-D semiconducting inorganic lead-chloride nanoribbons covalently bond to 1-D semiconducting organic π-aggregates. It shows high stability against light, heat, and moisture. After photoinduced electron transfer (PIET), it yields a long-lived charge-separated state with a broad absorption band covering the 200–900 nm region while increasing its conductance and photoconductance. This work is the first to modify the photoconductance of semiconductors by PIET. The observed increasing times of conductivity reached 3 orders of magnitude, which represents a record for photoswitchable semiconductors. The increasing photocurrent comes mainly from the semiconducting organic π-aggregates, which indicates a chance to improve the photocurrent by modifying the organic component. These findings contribute to the exploration of light absorbers for solar cells

Design Strategy for Improving Optical and Electrical Properties and Stability of Lead-Halide Semiconductors

Broad absorption, long-lived photogenerated carriers, high conductance, and high stability are all required for a light absorber toward its real application on solar cells. Inorganic–organic hybrid lead-halide materials have shown tremendous potential for applications in solar cells. This work offers a new design strategy to improve the absorption range, conductance, photoconductance, and stability of these materials. We synthesized a new photochromic lead-chloride semiconductor by incorporating a photoactive viologen zwitterion into a lead-chloride system in the coordinating mode. This semiconductor has a novel inorganic–organic hybrid structure, where 1-D semiconducting inorganic lead-chloride nanoribbons covalently bond to 1-D semiconducting organic π-aggregates. It shows high stability against light, heat, and moisture. After photoinduced electron transfer (PIET), it yields a long-lived charge-separated state with a broad absorption band covering the 200–900 nm region while increasing its conductance and photoconductance. This work is the first to modify the photoconductance of semiconductors by PIET. The observed increasing times of conductivity reached 3 orders of magnitude, which represents a record for photoswitchable semiconductors. The increasing photocurrent comes mainly from the semiconducting organic π-aggregates, which indicates a chance to improve the photocurrent by modifying the organic component. These findings contribute to the exploration of light absorbers for solar cells

Design Strategy for Improving Optical and Electrical Properties and Stability of Lead-Halide Semiconductors

Broad absorption, long-lived photogenerated carriers, high conductance, and high stability are all required for a light absorber toward its real application on solar cells. Inorganic–organic hybrid lead-halide materials have shown tremendous potential for applications in solar cells. This work offers a new design strategy to improve the absorption range, conductance, photoconductance, and stability of these materials. We synthesized a new photochromic lead-chloride semiconductor by incorporating a photoactive viologen zwitterion into a lead-chloride system in the coordinating mode. This semiconductor has a novel inorganic–organic hybrid structure, where 1-D semiconducting inorganic lead-chloride nanoribbons covalently bond to 1-D semiconducting organic π-aggregates. It shows high stability against light, heat, and moisture. After photoinduced electron transfer (PIET), it yields a long-lived charge-separated state with a broad absorption band covering the 200–900 nm region while increasing its conductance and photoconductance. This work is the first to modify the photoconductance of semiconductors by PIET. The observed increasing times of conductivity reached 3 orders of magnitude, which represents a record for photoswitchable semiconductors. The increasing photocurrent comes mainly from the semiconducting organic π-aggregates, which indicates a chance to improve the photocurrent by modifying the organic component. These findings contribute to the exploration of light absorbers for solar cells

High Anhydrous Proton Conductivity of Imidazole-Loaded Mesoporous Polyimides over a Wide Range from Subzero to Moderate Temperature

On-board fuel cell technology requires proton conducting materials with high conductivity not only at intermediate temperatures for work but also at room temperature and even at subzero temperature for startup when exposed to the colder climate. To develop such materials is still challenging because many promising candidates for the proton transport on the basis of extended microstructures of water molecules suffer from significant damage by heat at temperatures above 80 °C or by freeze below −5 °C. Here we show imidazole loaded tetrahedral polyimides with mesopores and good stability (Im@Td-PNDI <b>1</b> and Im@Td-PPI <b>2</b>) exhibiting a high anhydrous proton conductivity over a wide temperature range from −40 to 90 °C. Among all anhydrous proton conductors, the conductivity of <b>2</b> is the highest at temperatures below 40 °C and comparable with the best materials, His@[Al­(OH)­(1,4-ndc)]_<i>n</i> and [Zn₃(H₂PO₄)₆(H₂O)₃]­(Hbim), above 40 °C

Oxychalcogenide BaGeOSe₂: Highly Distorted Mixed-Anion Building Units Leading to a Large Second-Harmonic Generation Response

Oxychalcogenide BaGeOSe₂: Highly Distorted Mixed-Anion Building Units Leading to a Large Second-Harmonic Generation Respons