Research Expertise and Interest

inorganic and materials chemistry, synthesis of inorganic molecules and higher dimensional solids, precise tailoring of chemical and physical properties, gas storage, molecular separations and catalysis in porous materials, magnetic and conductive materials

Research Description

Research in the Long Group is focused on controlling chemical structure and function through molecular design. Within this paradigm, they employ the principles of coordination chemistry in the tailored synthesis of atomically precise molecules and materials with programmed properties, with the goal of achieving fundamental advances relevant to our technological, environmental, and energy future. They are developing new porous materials for diverse applications ranging from gas storage to water purification. They are also creating new high-performance magnetic molecules and conductive extended solids. They employ a range of physical methods to analyze and characterize their materials comprehensively, including gas adsorption analysis, x-ray and neutron diffraction, various spectroscopic techniques, and SQUID magnetometry. Current focus areas are highlighted below. For more information and a full list of publications, please visit the group website.

Functional Metal–Organic Frameworks
Metal–organic frameworks (MOFs) are crystalline, permanently porous solids with internal pore structures and local chemistries that can be precisely tuned using coordination chemistry. Guided by insights from molecular chemistry, biology, and traditional solid-state chemistry, they are harnessing the unique properties of MOFs (i) to achieve new mechanisms for cooperative gas adsorption reminiscent of those employed by natural enzymes; (ii) to design new porous magnets and electronic conductors; (iii) for applications in catalysis; and (iv) featuring coordinatively unsaturated metal sites and unique pore architectures for selective guest adsorption relevant to gas storage and molecular separations. They are also developing new methods to produce these adsorbents in predictable nanocrystalline forms to optimize macroscopic properties relevant for industrial applications, such as crystallite size and morphology, and incorporating these nanocrystals within polymer membranes to generate mixed-matrix membranes that exhibit exceptional selectivities and permeabilities for industrially relevant separations.

Quantum Magnetism in Molecular Materials
They are employing novel design principles and architectures precisely chosen to enhance operating temperatures within a class of compounds known as single-molecule magnets. These molecules exhibit a strong directional dependence to their magnetization (known as magnetic anisotropy) and magnetic hysteresis, previously thought to be exclusive to bulk magnets. As such, single-molecule magnets are of great interest for applications including quantum computing, quantum sensing, and even dark matter detection. Through the judicious manipulation of ligand fields, electronic structure, and magnetic interactions, they are endeavoring to create systems exhibiting striking new magnetic behaviors. Design motifs including highly anisotropic lanthanide ions, low-coordinate transition metals, and radical bridges are used to access unprecedented electronic structures, exceptionally strong magnetic exchange coupling, and anisotropies rivaling those of commercial permanent magnets. They are also creating new systems with potential applications in quantum information science, with the central hypothesis that molecular design principles established for single-molecule magnets can be adapted to give rise to a generation of electronic spin qubits with atomically precise local and global structures.

Porous Polymers and Composite Membranes
They are developing an emerging class of tunable porous network polymers known as porous aromatic frameworks (PAFs) for the selective recovery of diverse solutes for separation and purification applications, such as water remediation and the recovery of high-value metal ions from aqueous waste streams. PAFs exhibit high surface areas and are buttressed by strong covalent bonds, rendering them extremely robust under harsh conditions, including strongly acidic, alkaline, and humid environments. They are also incorporating these functionalized PAFs into polymer membranes to generate high-performance composite membranes for implementation in novel and efficient membrane-based separation strategies.