Banghao Chen - Academia.edu (original) (raw)

Papers by Banghao Chen

Research paper thumbnail of CCDC 1982254: Experimental Crystal Structure Determination

Research paper thumbnail of CCDC 1498689: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1498685: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1538293: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1580794: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1497737: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1548854: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1033529: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 840337: Experimental Crystal Structure Determination

Related Article: C.D.L.Saunders, L.E.Longobardi, N.Burford, M.D.Lumsden, U.Werner-Zwanziger, Bang... more Related Article: C.D.L.Saunders, L.E.Longobardi, N.Burford, M.D.Lumsden, U.Werner-Zwanziger, Banghao Chen, R.McDonald|2011|Inorg.Chem.|50|2799|doi:10.1021/ic101892x

Research paper thumbnail of Highly Luminescent Bulk Quantum Materials Based on Zero-Dimensional Organic Tin Halide Perovskites

Bulk quantum materials based on zero-dimensional (0D) lead-free organic tin halide perovskites ha... more Bulk quantum materials based on zero-dimensional (0D) lead-free organic tin halide perovskites have been developed for the first time, which give broadband Gaussian-shaped and strongly Stokes shifted emissions with quantum efficiencies of up to near-unity at room temperature due to excited state structural reorganization.

Research paper thumbnail of 0D and 2D: The Cases of Phenylethylammonium Tin Bromide Hybrids

Chemistry of Materials

Tin halide perovskites and perovskite-related materials have emerged as promising lead-free hybri... more Tin halide perovskites and perovskite-related materials have emerged as promising lead-free hybrid materials for various op-toelectronic applications. While remarkable progress has been achieved in...

Research paper thumbnail of Water and Ion Transport through the Glass Transition in Polyelectrolyte Complexes

Research paper thumbnail of Chemical interaction and enhanced interfacial ion transport in a ceramic nanofiber–polymer composite electrolyte for all-solid-state lithium metal batteries

Journal of Materials Chemistry A

This article shows strong chemical interaction between a ceramic and polymer in a solid-state com... more This article shows strong chemical interaction between a ceramic and polymer in a solid-state composite electrolyte and three Li-ion transport pathways.

Research paper thumbnail of Luminescent Quantum Dots Stabilized by NHeterocyclic Carbene Polymer Ligands

We have tested the ability of N-heterocyclic carbene (NHC)-modified ligands to coordinate and sta... more We have tested the ability of N-heterocyclic carbene (NHC)-modified ligands to coordinate and stabilize luminescent CdSe-ZnS core-shell quantum dot (QD) dispersions in hydrophilic media. In particular, we probed the effects of ligand structure and coordination number on the coating affinity to the nanocrystals. We find that such NHC-based ligands rapidly coordinate onto the QDs (requiring ∼5-10 min of reaction time), which reflects the soft Lewis base nature of the NHC groups, with its two electrons sharing capacity. Removal of the hydrophobic cap and promotion of carbene-driven coordination on the nanocrystals have been verified by 1H NMR spectroscopy, while 13C NMR was used to identify the formation of carbene-Zn complexes. The newly coated QD dispersions exhibit great long-term colloidal stability over a wide range of conditions. Additionally, we find that coordination onto the QD surfaces affects the optical and spectroscopic properties of the nanocrystals. These include a size-dependent red-shift of the absorption and fluorescence spectra and a pronounced increase in the measured fluorescence intensity when the samples are stored under white light exposure compared to those stored in the dark.

Research paper thumbnail of Carrier Density, Effective Mass, and Nuclear Relaxation Pathways in Plasmonic Sn:In2O3 Nanocrystals

Correlating changes in carrier density arising from incorporating dopant ions into the lattice of... more Correlating changes in carrier density arising from incorporating dopant ions into the lattice of a plasmonic semiconductor nanocrystals (NCs) with the observed physical properties at the elemental...

Research paper thumbnail of Bulk Assemblies of Lead Bromide Trimer Clusters with Geometry-Dependent Photophysical Properties

Chemistry of Materials

Single crystalline bulk assemblies of metal halide clusters show great promise as highly efficien... more Single crystalline bulk assemblies of metal halide clusters show great promise as highly efficient light emitters with tunable photophysical properties. However, synthetic control of the geometry of clusters in a rational manner has not been well established, and the relationships between the photophysical properties and structures of this emerging class of zero-dimensional (0D) materials are still not well understood. Here, we report the synthesis and characterization of two bulk assemblies of lead bromide clusters, (bmpy)6[Pb3Br12] (T1) and (bmpy)9[ZnBr4]2[Pb3Br11] (T2) (bmpy: 1-butyl-1methylpyrrolidinium), which contain metal halide trimer clusters with different geometries. T1 with chain-shaped [Pb3Br12] 6clusters is not emissive at room temperature, while T2 with triangle-shaped [Pb3Br11] 5-clusters exhibits yellowish-green emission peaked at 564 nm with a photoluminescence quantum efficiency (PLQE) of 7 % at room temperature. Detailed analysis of the structural and photophysical properties show that the photophysical properties and excited-state dynamics of these materials are highly dependent on the geometry of metal halide clusters.

Research paper thumbnail of High-Temperature Grafting Silylation for Minimizing Leaching of Acid Functionality from Hydrophobic Mesoporous Silicas Used as Catalysts in the Liquid Phase

Langmuir

Ordered-hexagonal silica materials, such as Mobil crystalline material-41 and Santa Barbara amorp... more Ordered-hexagonal silica materials, such as Mobil crystalline material-41 and Santa Barbara amorphous-15, have important applications in heterogeneous catalysis and biomass conversion due to their chemical stability and mesoporous structure. Low-temperature grafting (LG) is one of the most common functionalization methods used to modify the acidity/basicity or hydrophobicity/hydrophilicity of the surface. However, the materials prepared by this method are prone to leaching of functional groups into the reaction medium. The exact nature of the leaching phenomenon has not been fully addressed in the literature. In this contribution, we have investigated this process at the molecular level by combining well-controlled reaction experiments and several characterization techniques (Fourier transform infrared, 1H-29Si cross-polarization magic-angle spinning NMR, X-ray diffraction, thermogravimetric analysis, and N2 adsorption-desorption). We have found that leaching is originated by the presence of terminal surface silanols, which render the catalysts susceptible to the attack of water and polar compounds. Hence, instead of simple detaching of functional groups, leaching can be better described as a partial dissolution of the surface layers of the silica, which of course also removes the functional groups during this process. Therefore, an effective strategy to minimize leaching is to reduce the density of free silanols via full functionalization of the surface. We propose a novel silylation method, high-temperature grafting, which allows the grafting process to be conducted at high temperatures (180 °C) under solvent-free conditions. By this method, a more complete silylation of surface silanols can be obtained. Consequently, the samples prepared by this high-temperature grafting method show to be highly stable during acid-catalyzed alkylation reaction, conducted under severe conditions (high temperature and in the presence of polar solvents).

Research paper thumbnail of Copper(I) and gold(I) thiolate precursors to bimetallic nanoparticles

Polyhedron

Abstract Copper(I) and gold(I) thiolates were synthesized in quantitative or near-quantitative yi... more Abstract Copper(I) and gold(I) thiolates were synthesized in quantitative or near-quantitative yield by the direct reaction of aqueous Cu(NO3)2 or HAuCl4 with aqueous thiols HSCH2CH2OH and HSCH2CH2OCH2CH2OH. The resulting highly insoluble thiolates had spectroscopic and bulk characteristics consistent with the formation of coordination polymers of general formula [M(SR)]n. The gold(I) thiolates were found to be amorphous solids with significant aurophilic interactions. The copper(I) thiolates, however, formed crystalline solids without discernible cuprophilic interactions. Characterization of the solid state structure of these latter thiolates showed that they consisted of covalently linked ca. two-atom thick Cu–S layers separated by layers of hydrogen bonded thiol side chains.

Research paper thumbnail of Scaling Laws for Polymer Chains Grafted onto Nanoparticles

Macromolecular Chemistry and Physics

Research paper thumbnail of Characterization of the Ligand Capping of Hydrophobic CdSe–ZnS Quantum Dots Using NMR Spectroscopy

Chemistry of Materials

We have combined a few advanced solution phase NMR spectroscopy techniques, namely, 1H, 31P, hete... more We have combined a few advanced solution phase NMR spectroscopy techniques, namely, 1H, 31P, heteronuclear single quantum coherence (HSQC), and diffusion ordered spectroscopy (DOSY), to probe the composition of the organic capping layer on colloidal CdSe–ZnS core–shell quantum dots grown via the “hot injection” route. Combining solution phase 31P and 1H NMR with DOSY, we are able to distinguish between free ligands and those coordinated on the QD surfaces. Furthermore, when those NMR measurements are complemented with matrix-assisted laser desorption ionization (MALDI) and FTIR data, we find that the organic shell of the as-prepared QDs consists of a mixture of tri-n-octylphosphine oxide (TOPO), tri-n-octylphosphine (TOP), alkyl amine, and alkyl phosphonic acid (L- and X-type ligands); the latter molecules are usually added during growth at a rather small concentration to improve the quality of the prepared nanocrystals. However, NMR data collected from QD dispersions subjected to two or three rounds of p...

Research paper thumbnail of CCDC 1982254: Experimental Crystal Structure Determination

Research paper thumbnail of CCDC 1498689: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1498685: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1538293: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1580794: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1497737: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1548854: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1033529: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 840337: Experimental Crystal Structure Determination

Related Article: C.D.L.Saunders, L.E.Longobardi, N.Burford, M.D.Lumsden, U.Werner-Zwanziger, Bang... more Related Article: C.D.L.Saunders, L.E.Longobardi, N.Burford, M.D.Lumsden, U.Werner-Zwanziger, Banghao Chen, R.McDonald|2011|Inorg.Chem.|50|2799|doi:10.1021/ic101892x

Research paper thumbnail of Highly Luminescent Bulk Quantum Materials Based on Zero-Dimensional Organic Tin Halide Perovskites

Bulk quantum materials based on zero-dimensional (0D) lead-free organic tin halide perovskites ha... more Bulk quantum materials based on zero-dimensional (0D) lead-free organic tin halide perovskites have been developed for the first time, which give broadband Gaussian-shaped and strongly Stokes shifted emissions with quantum efficiencies of up to near-unity at room temperature due to excited state structural reorganization.

Research paper thumbnail of 0D and 2D: The Cases of Phenylethylammonium Tin Bromide Hybrids

Chemistry of Materials

Tin halide perovskites and perovskite-related materials have emerged as promising lead-free hybri... more Tin halide perovskites and perovskite-related materials have emerged as promising lead-free hybrid materials for various op-toelectronic applications. While remarkable progress has been achieved in...

Research paper thumbnail of Water and Ion Transport through the Glass Transition in Polyelectrolyte Complexes

Research paper thumbnail of Chemical interaction and enhanced interfacial ion transport in a ceramic nanofiber–polymer composite electrolyte for all-solid-state lithium metal batteries

Journal of Materials Chemistry A

This article shows strong chemical interaction between a ceramic and polymer in a solid-state com... more This article shows strong chemical interaction between a ceramic and polymer in a solid-state composite electrolyte and three Li-ion transport pathways.

Research paper thumbnail of Luminescent Quantum Dots Stabilized by NHeterocyclic Carbene Polymer Ligands

We have tested the ability of N-heterocyclic carbene (NHC)-modified ligands to coordinate and sta... more We have tested the ability of N-heterocyclic carbene (NHC)-modified ligands to coordinate and stabilize luminescent CdSe-ZnS core-shell quantum dot (QD) dispersions in hydrophilic media. In particular, we probed the effects of ligand structure and coordination number on the coating affinity to the nanocrystals. We find that such NHC-based ligands rapidly coordinate onto the QDs (requiring ∼5-10 min of reaction time), which reflects the soft Lewis base nature of the NHC groups, with its two electrons sharing capacity. Removal of the hydrophobic cap and promotion of carbene-driven coordination on the nanocrystals have been verified by 1H NMR spectroscopy, while 13C NMR was used to identify the formation of carbene-Zn complexes. The newly coated QD dispersions exhibit great long-term colloidal stability over a wide range of conditions. Additionally, we find that coordination onto the QD surfaces affects the optical and spectroscopic properties of the nanocrystals. These include a size-dependent red-shift of the absorption and fluorescence spectra and a pronounced increase in the measured fluorescence intensity when the samples are stored under white light exposure compared to those stored in the dark.

Research paper thumbnail of Carrier Density, Effective Mass, and Nuclear Relaxation Pathways in Plasmonic Sn:In2O3 Nanocrystals

Correlating changes in carrier density arising from incorporating dopant ions into the lattice of... more Correlating changes in carrier density arising from incorporating dopant ions into the lattice of a plasmonic semiconductor nanocrystals (NCs) with the observed physical properties at the elemental...

Research paper thumbnail of Bulk Assemblies of Lead Bromide Trimer Clusters with Geometry-Dependent Photophysical Properties

Chemistry of Materials

Single crystalline bulk assemblies of metal halide clusters show great promise as highly efficien... more Single crystalline bulk assemblies of metal halide clusters show great promise as highly efficient light emitters with tunable photophysical properties. However, synthetic control of the geometry of clusters in a rational manner has not been well established, and the relationships between the photophysical properties and structures of this emerging class of zero-dimensional (0D) materials are still not well understood. Here, we report the synthesis and characterization of two bulk assemblies of lead bromide clusters, (bmpy)6[Pb3Br12] (T1) and (bmpy)9[ZnBr4]2[Pb3Br11] (T2) (bmpy: 1-butyl-1methylpyrrolidinium), which contain metal halide trimer clusters with different geometries. T1 with chain-shaped [Pb3Br12] 6clusters is not emissive at room temperature, while T2 with triangle-shaped [Pb3Br11] 5-clusters exhibits yellowish-green emission peaked at 564 nm with a photoluminescence quantum efficiency (PLQE) of 7 % at room temperature. Detailed analysis of the structural and photophysical properties show that the photophysical properties and excited-state dynamics of these materials are highly dependent on the geometry of metal halide clusters.

Research paper thumbnail of High-Temperature Grafting Silylation for Minimizing Leaching of Acid Functionality from Hydrophobic Mesoporous Silicas Used as Catalysts in the Liquid Phase

Langmuir

Ordered-hexagonal silica materials, such as Mobil crystalline material-41 and Santa Barbara amorp... more Ordered-hexagonal silica materials, such as Mobil crystalline material-41 and Santa Barbara amorphous-15, have important applications in heterogeneous catalysis and biomass conversion due to their chemical stability and mesoporous structure. Low-temperature grafting (LG) is one of the most common functionalization methods used to modify the acidity/basicity or hydrophobicity/hydrophilicity of the surface. However, the materials prepared by this method are prone to leaching of functional groups into the reaction medium. The exact nature of the leaching phenomenon has not been fully addressed in the literature. In this contribution, we have investigated this process at the molecular level by combining well-controlled reaction experiments and several characterization techniques (Fourier transform infrared, 1H-29Si cross-polarization magic-angle spinning NMR, X-ray diffraction, thermogravimetric analysis, and N2 adsorption-desorption). We have found that leaching is originated by the presence of terminal surface silanols, which render the catalysts susceptible to the attack of water and polar compounds. Hence, instead of simple detaching of functional groups, leaching can be better described as a partial dissolution of the surface layers of the silica, which of course also removes the functional groups during this process. Therefore, an effective strategy to minimize leaching is to reduce the density of free silanols via full functionalization of the surface. We propose a novel silylation method, high-temperature grafting, which allows the grafting process to be conducted at high temperatures (180 °C) under solvent-free conditions. By this method, a more complete silylation of surface silanols can be obtained. Consequently, the samples prepared by this high-temperature grafting method show to be highly stable during acid-catalyzed alkylation reaction, conducted under severe conditions (high temperature and in the presence of polar solvents).

Research paper thumbnail of Copper(I) and gold(I) thiolate precursors to bimetallic nanoparticles

Polyhedron

Abstract Copper(I) and gold(I) thiolates were synthesized in quantitative or near-quantitative yi... more Abstract Copper(I) and gold(I) thiolates were synthesized in quantitative or near-quantitative yield by the direct reaction of aqueous Cu(NO3)2 or HAuCl4 with aqueous thiols HSCH2CH2OH and HSCH2CH2OCH2CH2OH. The resulting highly insoluble thiolates had spectroscopic and bulk characteristics consistent with the formation of coordination polymers of general formula [M(SR)]n. The gold(I) thiolates were found to be amorphous solids with significant aurophilic interactions. The copper(I) thiolates, however, formed crystalline solids without discernible cuprophilic interactions. Characterization of the solid state structure of these latter thiolates showed that they consisted of covalently linked ca. two-atom thick Cu–S layers separated by layers of hydrogen bonded thiol side chains.

Research paper thumbnail of Scaling Laws for Polymer Chains Grafted onto Nanoparticles

Macromolecular Chemistry and Physics

Research paper thumbnail of Characterization of the Ligand Capping of Hydrophobic CdSe–ZnS Quantum Dots Using NMR Spectroscopy

Chemistry of Materials

We have combined a few advanced solution phase NMR spectroscopy techniques, namely, 1H, 31P, hete... more We have combined a few advanced solution phase NMR spectroscopy techniques, namely, 1H, 31P, heteronuclear single quantum coherence (HSQC), and diffusion ordered spectroscopy (DOSY), to probe the composition of the organic capping layer on colloidal CdSe–ZnS core–shell quantum dots grown via the “hot injection” route. Combining solution phase 31P and 1H NMR with DOSY, we are able to distinguish between free ligands and those coordinated on the QD surfaces. Furthermore, when those NMR measurements are complemented with matrix-assisted laser desorption ionization (MALDI) and FTIR data, we find that the organic shell of the as-prepared QDs consists of a mixture of tri-n-octylphosphine oxide (TOPO), tri-n-octylphosphine (TOP), alkyl amine, and alkyl phosphonic acid (L- and X-type ligands); the latter molecules are usually added during growth at a rather small concentration to improve the quality of the prepared nanocrystals. However, NMR data collected from QD dispersions subjected to two or three rounds of p...