Pseudocarbynes: A New Class of Carbon-chain Materials

Pseudocarbynes: A New Class of Carbon-chain Materials Pseudocarbynes: A New Class of Carbon-chain Materials 1. Abstract: The ability of carbon to bond with itself in nearly limitless ways helps explain its myriad structures and technological applications. Success in preparing 2D- and 3D-carbon materials such as fullerenes, nanotubes, and graphene makes it astounding that the simplest allotrope, a one-dimensional chain of sp-hybridized carbon known as carbyne, has long defied isolation and characterization. Inspired by a recent report of the synthesis of solid carbyne, which we question, we hypothesize that an entirely new class of molecules and materials exists in which carbon chains are stabilized by metal clusters coordinated along the chain. We call these molecules and materials, which are carbyne-based, pseudocarbynes. Interactions between the carbon chain and metal clusters are synergistic, leading to novel emergent physical and chemical properties we suspect approach the unprecedented strength, elastic modulus, and stiffness predicted for carbyne and include exemplary nonlinear optical and electronic properties. Pseudocarbynes also serve as prototypical models to explore fundamental chemical questions such as how the hybridization of carbon changes during reactions, which factors dictate hybridization preferences, and how to stabilize reactive species. Furthermore, the conjugated C C bonds of pseudocarbynes may be harnessed as synthetic handles in chemical synthesis to access new organic molecules and materials. This project, in the Science and Engineering Research emphasis area, will create, characterize, and utilize pseudocarbynes via an integrated program of experimental and theoretical research with three goals: 1) integrate computational design strategies and cutting-edge laser ablation methods to produce pseudocarbynes and other metal-carbon materials with desired chemical, electrical, optical, and physical properties; 2) define the synergistic metal-carbon interactions in pseudocarbynes and articulate connections between bonding and physicochemical properties; 3) employ pseudocarbynes as model materials to define the factors that dictate hybridization of carbon in chemical reactions, to explain astrophysical phenomena in the interstellar medium, and to construct molecular and optoelectronic devices. 2. Unique Aspects: The proposed work requires a broad set of scientific skills that include computational and experimental expertise in metal cluster chemistry, carbon chemistry, high-energy syntheses, and advanced spectroscopic and microscopic characterization of materials. Our team contains this diverse expertise, allowing us to both design and synthesize pseudocarbyne structures using an atom-by-atom, computationally driven approach and to employ in situ spectroscopic studies to define the mechanisms in these high-energy syntheses. Thus, the project uniquely combines discovery of new materials with development of fundamental mechanistic insight into the formation of carbon structures. 3. Key Personnel: The core team is at ASU. P.I. Anne Jones, Assoc. Prof. (purification and metal cluster reactivity) will have primary responsibility for the proposed research. Co-Is: Profs. Peter Buseck (electron microscopy); Scott Sayres (laser ablation synthesis, ultrafast spectroscopy); Timothy Steimle (laser ablation synthesis, optical spectroscopy); and Dr. Pilarisetty Tarakeshwar (theory and computational chemistry). Prof. Moreno Menghetti (nanomaterials) from University of Padova, Italy is collaborating in an unfunded capacity. 4. Budget: Project Total: $1,838,045. Request from WMFK: $1,000,000 (Personnel- $862,402; Operations- $137,598). Committed institutional support: $838,045. 5. Justification for WMFK Support: NSF reviewers of a prior proposal considered the idea innovative and exciting but too risky for funding without more preliminary data. However, obtaining such data requires funding for investigators and access to expensive facilities; so we are in a chicken-egg dilemma. WMFK support would allow us to bypass that dilemma.