Spin crossover frameworks

The incorporation of two terminal pyrazole or triazole rings into the ter-pyridine framework leads to a diversity of spin crossover behaviour not seen, for example, in the bis(thiazolyl) systems discussed above. It is likely that the presence of a non-coordinating >NH group and its involvement in hydrogen bonding gives rise to the striking effects. For a series of salts of [Fe(bpp)2]2+ (bpp is 2,6-bis(pyrazol-3- yl)pyridine 58) a marked dependence of the spin state on the anion and the extent of hydration has been observed [85-88]. 

A. Choudhury, S. Natarajan, and C.N.R. Rao, An Open-framework Iron Phosphate with Large Voids, Exhibiting Spin-crossover. Chem. Commun., 1999, 1305-1306. 

GJ. Haider, C.J. Kepert, B. Moubaraki, K.S. Murray, and J.D. Cashion, Guest-dependent Spin Crossover in a Nanoporous Molecular Framework Material. Science, 2002, 298, 1762-1765. 

Figure 1.18 Two-step spin crossover in the interpenetrated square grid framework [Fe (bpe)2(NCS)2] (guest) (SCOF-4 shown in the background viewed down the ID pores). The switching in this porous system proceeds from fully high-spin (right) to fully low-spin (left) via a chequerboard-type arrangement of high-spin and low-spin Fe nodes (centre). Reprinted with permission from G.J. Haider, K.W. Chapman, S.M. Neville, B. Moubaraki, K.S. Murray, J.F. Letard and C.J. Kepert, /. Am. Chem. Soc., 130,17552. Copyright (2008) American Chemical Society...

Haider, G. J., Kepert, C. J., Moubaraki, B., Murray, K. S. and Cashion, J. D., Guest-dependant spin crossover in a nanoporous molecular framework material. Science, 2002, 298, 1762-1765. 

D. J., Haider, G. J., Chapman, K. W., Moubaraki, B., Murray, K. S., Letard, J. F., and Kepert, C. J. Dynamic interplay between spin-crossover and host-guest function in a nanoporous metal-organic framework material. J Am Chem Soc 131, 10998-11009 (2009) (e) Maspoch, D., Ruiz-Molina, D., Wurst, K., Domingo, N., CavaUini, M.,... 

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