Journal
INORGANICA CHIMICA ACTA
Volume 363, Issue 13, Pages 3338-3344Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.ica.2010.06.016
Keywords
Photoacoustic calorimetry; Mepepy ligand; Salten mepepy complex; Photo-isomerization; Spin crossover; Thermodynamics
Categories
Funding
- US Department of Defense [HDTRA1-08-C-0035]
Ask authors/readers for more resources
The complex [Fe(III)(salten)(mepepy)] BPh(4) (salten = 4-azaheptamethylene-1,7-bis(salicylideneiminate; mepepy = 1-(pyridin-4-yl)-2-(N-methylpyrrol-2-yl)-ethene; BPh(4) = tetraphenyl borate) has been investigated to determine the volume and enthalpy changes associated with the room temperature photoinduced spin crossover. Here we report the photophysical properties of the trans to cis isomerization of the mepepy ligand as well as the spin crossover of the Fe(III)(salten)(mepepy) complex in acetonitrile: water mixtures using photoacoustic calorimetry (PAC). The PAC studies indicate that the trans to cis transition of the mepepy ligand occurs faster than the similar to 20 ns response time of the acoustic detector and gives rise to a negligible volume change (0.7 +/- 0.3 mL mol(-1)) and an enthalpy change of 33 +/- 10 kcal mol(-1). These results are consistent with the loss of a charge assisted hydrogen bond between a water molecule and the pyridyl ring of the mepepy upon photoisomerization. In the case of Fe(III)(salten)( mepepy) photoexcitation, PAC results indicate that the high-spin to low-spin transition, also occurring in less than or similar to 20 ns, gives rise to small volume and enthalpy changes (0.9 mL mol(-1) and 4 kcal mol(-1)). Analysis of the results indicate that the observed thermodynamics are related to a distortion of the Fe(II)(salten)(mepepy) complex associated with the cleavage of an Fe center dot center dot center dot N bond upon spin conversion. (C) 2010 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available