Intellectural Merits. Magnetic materials are worth billions in existing technologies. Chemical structure-based designs of new materials have much promise for new, useful types of electronic behavior. The PI proposes to make molecules with attached functional groups, which give specific magnetic and/or conductive properties. Stable organic radicals will be synthesized that are expected to self-assemble, for example, by using strongly directional hydrogen bonds. These organic pure solids, mixed solids, and hybrid systems (polymers containing radicals) will be tested for magnetic behavior and some for conductivity of electrical current as well. The most important scientific goals are: (1) to find good synthetic and purification methods to give materials that are stable and have potentially useful magneto-electronic properties; and (2) to discover new relationships linking molecular structure and crystal packing to magnetic and/or conductive properties.

Broader Impacts. Graduate students in this project will benefit from international exchange of expertise and collaborative ties, in particular with scientists from Brazil and Japan. Training will be highly interdisciplinary, including ways to make molecules, to determine how they assemble into solid packing patterns, and to correlate the patterns with magnetic or conductive behavior. Interdisciplinary training is vital in the modern techno-scientific marketplace, where projects have short timelines and workers must be adaptable and multi-talented. Communication skills will be emphasized by frequent group presentations, as well as presentations at national, regional, and/or local meetings. The group has in recent years had more women than men, a reversal of the situation from 20 years ago. This made the group a "magnet" for other women to feel comfortable in joining a group that does much organic synthesis and math-oriented physical chemistry. For example, four of five Ph.D. degrees completed during 2006 in the Lahti group went to women. Interest in the work by female potential graduate students in recent entering classes has remained strong. The proposed work will also be linked to efforts to attract students from the UMass-Amherst-led Northeast Alliance for Graduate Education and the Professoriate (NEAGEP), an NSF-supported program that funds under-represented minority groups to pursue graduate scientific careers on our campus (www.neagep.org). Dr. Lahti and his group have been part of on-campus hospitability and recruiting of visiting students who are considering NEAGEP. This program will be an important resource for recruiting graduate student candidates from under-represented minority backgrounds into the field of materials science.

Project Report

This project aimed to make new magnetic materials by assembling small molecule building blocks. The main overall goal was to find ways of assembly such that the new material would have magnetic properties more than just the sum of the individual pieces. Identifying which types of assembly give reproducible or dependable magnetic behavior is very important. We found that we could increase the strength of magnetic interaction between small molecule spin units, by applying pressure (collaboration with Schlueter at Argonne National Laboratory). The specific material tested has one of the strongest ferromagnetic (all spins line up in parallel) chain-type interactions between spins that is known for organic "soft" matter magnets. We found that we could "blend" similar but non-identical small molecule spin units into solids with varying composition. The magnetism in these "blended" solids showed a dependable, nearly linear variation in magnetic response. This allows tunable magnetism, a property that is quite difficult to get with pure solid materials, especially "soft materials" that can be synthesized by room temperature methods (collaboration with multiple Brazilian scientists). We found that we could blend metal ions (not strongly magnetic by themselves) with small organic molecule spin units (also not strong magnetic alone) to give a new, chain-like magnetic material that gives a very strong magnetic response that can be seen at 13 K (better than liquid helium used for MRI instruments at present, not yet so good as desirable liquid nitrogen temperatures that people are seeking to use for new materials). This involved collaboration with multiple Brazilian scientists. We found that molecules having multiple "extra" electrons could be immobilized and stabilized in a commercial polymer solid, and the interaction between the electrons detected by examining changes in color as functions of temperature and strong external magnetic field. This could be used for a field or temperature detection behavior (collaboration with U-Tennesee's Jan Musfeldt). This work primarily impacts basic understanding of materials chemistry and materials physics -- it does not in itself directly provide applications. The solid state "blend" methods used to tune magnetic behavior should be useful to tune other electronic properties, and be applicable in the rapidly growing area of organic electronics (used, for example, in the latest generations of HDTV and smart phone displays). Two foreign graduate students in the UMass Amherst graduate program, three USA undergraduate students, one foreign postdoctoral associate, two foreign visiting graduate students, and two visiting professor sabbaticals were supported during the course of this project. Mutiple new collaborative connections were forged in Brazil, that remain ongoing.

Agency
National Science Foundation (NSF)
Institute
Division of Chemistry (CHE)
Application #
0809791
Program Officer
Tyrone D. Mitchell
Project Start
Project End
Budget Start
2008-09-01
Budget End
2013-08-31
Support Year
Fiscal Year
2008
Total Cost
$398,750
Indirect Cost
Name
University of Massachusetts Amherst
Department
Type
DUNS #
City
Amherst
State
MA
Country
United States
Zip Code
01003