Million-Fold Electrical Conductivity Enhancement in Fe[subscript 2](DEBDC) versus Mn[subscript 2](DEBDC) (E = S, O)

Abstract

Reaction of FeCl[subscript 2] and H[subscript 4]DSBDC (2,5-disulfhydrylbenzene-1,4-dicarboxylic acid) leads to the formation of Fe[subscript 2](DSBDC), an analogue of M[subscript 2](DOBDC) (MOF-74, DOBDC[superscript 4–] = 2,5-dihydroxybenzene-1,4-dicarboxylate). The bulk electrical conductivity values of both Fe2(DSBDC) and Fe[subscript 2](DOBDC) are ~6 orders of magnitude higher than those of the Mn[superscript 2+] analogues, Mn[subscript 2](DEBDC) (E = O, S). Because the metals are of the same formal oxidation state, the increase in conductivity is attributed to the loosely bound Fe[superscript 2+] β-spin electron. These results provide important insight for the rational design of conductive metal–organic frameworks, highlighting in particular the advantages of iron for synthesizing such materials.