Abstract
| Language | English |
|---|---|
| Pages | 3884-3893 |
| Number of pages | 10 |
| Journal | Journal of the American Chemical Society |
| Volume | 131 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - 25 Mar 2009 |
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Keywords
- spectroscopy
- diffraction
- proton transfer
- single-crystal
- neutron diffraction
- squaric acid
- bypridine
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Temperature- and pressure-induced proton transfer in the 1:1 adduct formed between squaric acid and 4,4'-bipyridine. / Martins, D.M.S.; Middlemiss, D.S.; Pulham, C.R.; Wilson, C.C.; Weller, M.T.; Henry, P.F.; Shankland, N.; Shankland, K.
In: Journal of the American Chemical Society, Vol. 131, No. 11, 25.03.2009, p. 3884-3893.Research output: Contribution to journal › Article
TY - JOUR
T1 - Temperature- and pressure-induced proton transfer in the 1:1 adduct formed between squaric acid and 4,4'-bipyridine
AU - Martins, D.M.S.
AU - Middlemiss, D.S.
AU - Pulham, C.R.
AU - Wilson, C.C.
AU - Weller, M.T.
AU - Henry, P.F.
AU - Shankland, N.
AU - Shankland, K.
N1 - Strathprints' policy is to record up to 8 authors per publication, plus any additional authors based at the University of Strathclyde. More authors may be listed on the official publication than appear in the Strathprints' record.
PY - 2009/3/25
Y1 - 2009/3/25
N2 - We have applied a combination of spectroscopic and diffraction methods to study the adduct formed between squaric acid and bypridine, which has been postulated to exhibit proton transfer associated with a single-crystal to single-crystal phase transition at ca. 450 K. A combination of X-ray single-crystal and very-high flux powder neutron diffraction data confirmed that a proton does transfer from the acid to the base in the high-temperature form. Powder X-ray diffraction measurements demonstrated that the transition was reversible but that a significant kinetic energy barrier must be overcome to revert to the original structure. Computational modeling is consistent with these results. Modeling also revealed that, while the proton transfer event would be strongly discouraged in the gas phase, it occurs in the solid state due to the increase in charge state of the molecular ions and their arrangement inside the lattice. The color change is attributed to a narrowing of the squaric acid to bipyridine charge-transfer energy gap. Finally, evidence for the possible existence of two further phases at high pressure is also presented.
AB - We have applied a combination of spectroscopic and diffraction methods to study the adduct formed between squaric acid and bypridine, which has been postulated to exhibit proton transfer associated with a single-crystal to single-crystal phase transition at ca. 450 K. A combination of X-ray single-crystal and very-high flux powder neutron diffraction data confirmed that a proton does transfer from the acid to the base in the high-temperature form. Powder X-ray diffraction measurements demonstrated that the transition was reversible but that a significant kinetic energy barrier must be overcome to revert to the original structure. Computational modeling is consistent with these results. Modeling also revealed that, while the proton transfer event would be strongly discouraged in the gas phase, it occurs in the solid state due to the increase in charge state of the molecular ions and their arrangement inside the lattice. The color change is attributed to a narrowing of the squaric acid to bipyridine charge-transfer energy gap. Finally, evidence for the possible existence of two further phases at high pressure is also presented.
KW - spectroscopy
KW - diffraction
KW - proton transfer
KW - single-crystal
KW - neutron diffraction
KW - squaric acid
KW - bypridine
U2 - 10.1021/ja8082973
DO - 10.1021/ja8082973
M3 - Article
VL - 131
SP - 3884
EP - 3893
JO - Journal of the American Chemical Society
T2 - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 11
ER -