초록
<P>A series of two-dimensional (2D) spin-crossover coordination polymers (SCO-CPs) [Fe<SUP>II</SUP>(TPE)(NCX)<SUB>2</SUB>]·solv (<B>1</B>: X = BH<SUB>3</SUB>, solv = H<SUB>2</SUB>O·2CH<SUB>3</SUB>OH·DMF; <B>2</B>: X = Se, solv = H<SUB>2</SUB>O·2CH<SUB>3</SUB>OH·0.5DMF; <B>3</B>: X = S, solv = H<SUB>2</SUB>O·2CH<SUB>3</SUB>OH·0.5DMF) were synthesized by employing 1,1,2,2-tetra(pyridin-4-yl)ethene (TPE) and pseudohalide (NCX<SUP>−</SUP>) coligands. Magnetic measurements indicated that complexes <B>1-3</B> exhibited SCO behaviors with diminishing thermal hysteresis (7/4/0 K) upon decreasing the ligand-field strength. The critical temperatures (<I>T</I><SUB>c</SUB>) during spin transition were found to be inversely proportional to the coordination ability parameters (<I>a</I>™) with a linear correlation. The guest effect was also investigated in the solvent-exchanged phases <B>1-SE</B>/<B>2-SE</B>/<B>3-SE</B> wherein the DMF molecules were replaced by methanol molecules. Compared with <B>1-3</B>, <B>1-SE</B>/<B>2-SE</B>/<B>3-SE</B> displayed more abrupt and complete single-step SCO behaviors but narrower thermal hysteretic loops. The results reported here demonstrate that the <I>T</I><SUB>c</SUB> values of these two families were dominated by the ligand-field strength of the NCX<SUP>−</SUP> anions (NCBH<SUB>3</SUB> > NCSe > NCS), whereas the guest effect only modulated the kinetic factor of the SCO nature in this system.</P><P>Graphic Abstract</P><P>Spin-crossover behaviors and guest effects were investigated in three Fe(<SMALL>II</SMALL>) two-dimensional coordination polymers based on the 1,1,2,2-tetra(pyridin-4-yl)ethene ligand.<BR/><IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=d4dt00204k'/><BR/></P>