Formation of a Reversible, Intramolecular Main-Group Metal–CO₂ Adduct

The P,P-chelated stannylene [(<i>i</i>-Pr₂P)₂N]₂Sn takes up 2 equiv of carbon dioxide (CO₂) to form an unusual product in which CO₂ binds to the Sn and P atoms, thus forming a six-membered ring complex. Gentle heating of the solid product releases CO₂, indicating that CO₂ is bound as an adduct to the main-group complex. The groups bound to the CO₂ fragment are not particularly sterically crowded or highly acidic, thus indicating that “frustrated” Lewis acid–base pairs are not required in the binding of CO₂ to main-group elements

Mechanically Encoded Cellular Shapes for Synthesis of Anisotropic Mesoporous Particles

The asymmetry that pervades molecular mechanisms of living systems increasingly informs the aims of synthetic chemistry, particularly in the development of catalysts, particles, nanomaterials, and their assemblies. For particle synthesis, overcoming viscous forces to produce complex, nonspherical shapes is particularly challenging; a problem that is continuously solved in nature when observing dynamic biological entities such as cells. Here we bridge these dynamics to synthetic chemistry and show that the intrinsic asymmetric shapes of erythrocytes can be directed, captured, and translated into composites and inorganic particles using a process of nanoscale silica-bioreplication. We show that crucial aspects in particle design such as particle–particle interactions, pore size, and macromolecular accessibility can be tuned using cellular responses. The durability of resultant particles provides opportunities for shape-preserving transformations into metallic, semiconductive, and ferromagnetic particles and assemblies. The ability to use cellular responses as “structure directing agents” offers an unprecedented toolset to design colloidal-scale materials

Role of Cu-Ion Doping in Cu-α-MnO₂ Nanowire Electrocatalysts for the Oxygen Reduction Reaction

The role of Cu-ion doping in α-MnO₂ electrocatalysts for the oxygen reduction reaction in alkaline electrolyte was investigated. Cu-doped α-MnO₂ nanowires (Cu-α-MnO₂) were prepared with varying amounts (up to ∼3%) of Cu²⁺ using a hydrothermal method. The electrocatalytic data indicate that Cu-α-MnO₂ nanowires have up to 74% higher terminal current densities, 2.5 times enhanced kinetic rate constants, and 66% lower charge transfer resistances that trend with Cu content, exceeding values attained by α-MnO₂ alone. The observed improvement in catalytic behavior correlates with an increase in Mn³⁺ content at the surface of the Cu-α-MnO₂ nanowires. The Mn³⁺/Mn⁴⁺ couple is the mediator for the rate-limiting redox-driven O₂/OH^– exchange. O₂ adsorbs via an axial site (the e_g orbital on the Mn³⁺ d⁴ ion) at the surface or at edge defects of the nanowire, and the increase in covalent nature of the nanowire with Cu-ion doping leads to stabilization of O₂ adsorbates and faster rates of reduction. A smaller crystallite size (roughly half) for Cu-α-MnO₂ leading to a higher density of (catalytic) edge defect sites was also observed. This work is applicable to other manganese oxide electrocatalysts and shows for the first time there is a correlation for manganese oxides between electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline electrolyte and an increase in Mn³⁺ character at the surface of the oxide

Porous One-Dimensional Nanostructures through Confined Cooperative Self-Assembly

We report a simple confined self-assembly process to synthesize nanoporous one-dimensional photoactive nanostructures. Through surfactant-assisted cooperative interactions (e.g., π–π stacking, ligand coordination, and so forth) of the macrocyclic building block, zinc meso-tetra (4-pyridyl) porphyrin (ZnTPyP), self-assembled ZnTPyP nanowires and nanorods with controlled diameters and aspect ratios are prepared. Electron microscopy characterization in combination with X-ray diffraction and gas sorption experiments indicate that these materials exhibit stable single-crystalline and high surface area nanoporous frameworks with well-defined external morphology. Optical characterizations using UV–vis spectroscopy and fluorescence imaging and spectroscopy show enhanced collective optical properties over the individual chromophores (ZnTPyP), favorable for exciton formation and transport

Synthesis and Characterization of Structurally Diverse Alkaline-Earth Salen Compounds for Subterranean Fluid Flow Tracking

A family of magnesium and calcium salen-derivatives was synthesized and characterized for use as subterranean fluid flow monitors. For the Mg complexes, di-<i>n</i>-butyl magnesium ([Mg­(Bu^<i>n</i>)₂]) was reacted with <i>N</i>,<i>N</i>′-ethylene bis­(salicylideneimine) (H₂-salen), <i>N</i>,<i>N</i>′-bis­(salicylidene)-1,2-phenylenediamine (H₂-saloPh), <i>N</i>,<i>N</i>′-bis­(3,5-di-<i>t</i>-butylsalicylidene)-ethylenediamine (H₂-salo-Bu^<i>t</i>), or <i>N</i>,<i>N</i>′-bis­(3,5-di-<i>t</i>-butylsalicylidene)-1,2-phenylenediamine (H₂-saloPh-Bu^<i>t</i>), and the products were identified by single-crystal X-ray diffraction as [(κ³-(O,N,N′),μ-(O′)­saloPh)­(μ-(O),(κ²-(N,N′),μ-(O′)­saloPh)₂­(μ-(O),κ³-(N,N′,O′)­saloPh′)­Mg₄]·2tol (<b>1</b>·2tol; saloPh′ = an alkyl-modified saloPh derivative generated in situ), [(κ⁴-(O,N,N′,O′)­saloPh)­Mg­(py)₂]·py (<b>2</b>·py), [(κ⁴-(O,N,N′,O′)­salo-Bu^<i>t</i>)­Mg­(py)₂] (<b>3</b>), [(κ⁴-(O,N,N′,O′)­saloPh-Bu^<i>t</i>)­Mg­(py)₂]·tol (<b>4</b>·tol), and [(κ³-(O,N,N′),μ-(O′)­saloPh-Bu^<i>t</i>)­Mg]₂ (<b>5</b>), where tol = toluene; py = pyridine. For the Ca species, a calcium amide was independently reacted with H₂-salo-Bu^<i>t</i> and H₂-saloPh-Bu^<i>t</i> to generate the crystallographcially characterized compounds: [(κ⁴-(O,N,N′,O′)­salo-Bu^<i>t</i>)­Ca­(py)₃] (<b>6</b>), [(κ⁴-(O,N,N′,O′)­saloPh-Bu^<i>t</i>)­Ca­(py)₃]·py (<b>7</b>·py). The bulk powders of these compounds were further characterized by a number of analytical tools, where <b>2</b>–<b>7</b> were found to be distinguishable by Fourier transform infrared and resonance Raman spectroscopies. Structural properties obtained from quantum calculations of gas-phase analogues are in good agreement with the single-crystal results. The potential utility of these compounds as taggants for monitoring subterranean fluid flows was demonstrated through a series of experiments to evaluate their stability to high temperature and pressure, interaction with mineral surfaces, and elution behavior from a loaded proppant pack

Metallic Cation-Mediated Entrapment of Nucleic Acids on Mesoporous Silica Surface: Application in Castration-Resistant Prostate Cancer

The use of exogenous nucleic acid technologies to modulate aberrant protein expression resulting from genetic mutations is a promising therapeutic approach for the treatment of diseases such as advanced prostate cancer (PC). The promise of nucleic-based therapeutics is dependent on the development of platforms that effectively protect nucleic acids from nuclease degradation and deliver the nucleic acids to the cytosol of target cells. In this work, we present the development of a divalent metal-mediated nucleic acid entrapment strategy with a porous silica matrix. This simple strategy results in efficient loading percentages of both siRNA (>60%) and mRNA (>80%) as well as their release within relevant biological environments (80%). Additionally, our data supports that the current method reduces endosomal entrapment and supports the lipid coating of mesoporous silica nanoparticles (LC-MSNs). The metal-enhanced nanosystem is assessed for biocompatibility, stability, and circulation within in vitro, ex ovo, and in vivo models of PC

Metallic Cation-Mediated Entrapment of Nucleic Acids on Mesoporous Silica Surface: Application in Castration-Resistant Prostate Cancer

The use of exogenous nucleic acid technologies to modulate aberrant protein expression resulting from genetic mutations is a promising therapeutic approach for the treatment of diseases such as advanced prostate cancer (PC). The promise of nucleic-based therapeutics is dependent on the development of platforms that effectively protect nucleic acids from nuclease degradation and deliver the nucleic acids to the cytosol of target cells. In this work, we present the development of a divalent metal-mediated nucleic acid entrapment strategy with a porous silica matrix. This simple strategy results in efficient loading percentages of both siRNA (>60%) and mRNA (>80%) as well as their release within relevant biological environments (80%). Additionally, our data supports that the current method reduces endosomal entrapment and supports the lipid coating of mesoporous silica nanoparticles (LC-MSNs). The metal-enhanced nanosystem is assessed for biocompatibility, stability, and circulation within in vitro, ex ovo, and in vivo models of PC

Metallic Cation-Mediated Entrapment of Nucleic Acids on Mesoporous Silica Surface: Application in Castration-Resistant Prostate Cancer

The use of exogenous nucleic acid technologies to modulate aberrant protein expression resulting from genetic mutations is a promising therapeutic approach for the treatment of diseases such as advanced prostate cancer (PC). The promise of nucleic-based therapeutics is dependent on the development of platforms that effectively protect nucleic acids from nuclease degradation and deliver the nucleic acids to the cytosol of target cells. In this work, we present the development of a divalent metal-mediated nucleic acid entrapment strategy with a porous silica matrix. This simple strategy results in efficient loading percentages of both siRNA (>60%) and mRNA (>80%) as well as their release within relevant biological environments (80%). Additionally, our data supports that the current method reduces endosomal entrapment and supports the lipid coating of mesoporous silica nanoparticles (LC-MSNs). The metal-enhanced nanosystem is assessed for biocompatibility, stability, and circulation within in vitro, ex ovo, and in vivo models of PC

Metallic Cation-Mediated Entrapment of Nucleic Acids on Mesoporous Silica Surface: Application in Castration-Resistant Prostate Cancer

The use of exogenous nucleic acid technologies to modulate aberrant protein expression resulting from genetic mutations is a promising therapeutic approach for the treatment of diseases such as advanced prostate cancer (PC). The promise of nucleic-based therapeutics is dependent on the development of platforms that effectively protect nucleic acids from nuclease degradation and deliver the nucleic acids to the cytosol of target cells. In this work, we present the development of a divalent metal-mediated nucleic acid entrapment strategy with a porous silica matrix. This simple strategy results in efficient loading percentages of both siRNA (>60%) and mRNA (>80%) as well as their release within relevant biological environments (80%). Additionally, our data supports that the current method reduces endosomal entrapment and supports the lipid coating of mesoporous silica nanoparticles (LC-MSNs). The metal-enhanced nanosystem is assessed for biocompatibility, stability, and circulation within in vitro, ex ovo, and in vivo models of PC

Metallic Cation-Mediated Entrapment of Nucleic Acids on Mesoporous Silica Surface: Application in Castration-Resistant Prostate Cancer

The use of exogenous nucleic acid technologies to modulate aberrant protein expression resulting from genetic mutations is a promising therapeutic approach for the treatment of diseases such as advanced prostate cancer (PC). The promise of nucleic-based therapeutics is dependent on the development of platforms that effectively protect nucleic acids from nuclease degradation and deliver the nucleic acids to the cytosol of target cells. In this work, we present the development of a divalent metal-mediated nucleic acid entrapment strategy with a porous silica matrix. This simple strategy results in efficient loading percentages of both siRNA (>60%) and mRNA (>80%) as well as their release within relevant biological environments (80%). Additionally, our data supports that the current method reduces endosomal entrapment and supports the lipid coating of mesoporous silica nanoparticles (LC-MSNs). The metal-enhanced nanosystem is assessed for biocompatibility, stability, and circulation within in vitro, ex ovo, and in vivo models of PC