posted on 2018-08-28, 18:00authored byRuilan Liu, Lili Zhao, Shihang Yu, Xi Liang, Zifeng Li, Gang Li
By
reaction of a newly designed organic ligand, [3-(naphthalene-1-carbonyl)-thioureido]
acetic acid (C10H7C(O)NHC(S)NHCH2COOH; H3L), with Cu(OAc)2, a metal–organic
framework [(CuI4CuII4L4)·3H2O]n (1) containing unique mixed-valence [CuI4Cu4IIL4] subunits has been successfully
synthesized and structurally characterized. MOF 1 displays
a three-dimensional open framework bearing one-dimensional channels.
Consequently, a new derivative MOF [CuI4CuII4L4]n-NH3 (2) is procured upon exposure of 1 to NH3 vapors from 28 wt % aqueous NH3 solution,
which bears 2 NH3 and 4 H2O molecules in accordance
with the elemental and thermal analyses. Both 1 and 2 exhibit relatively high water stability, whose proton conduction
properties under water vapor have been researched. Notably, 2 shows an ultrahigh proton conductivity of 1.13 × 10–2 S cm–1, which is 2 orders of magnitude
larger than that of MOF 1 (4.90 × 10–4 S cm–1) under 100 °C and 98% RH. On the basis
of the structural data, Ea values, H2O and ammonia vapor absorptions, and PXRD measurements, the
proton transfer mechanisms were suggested. This is an efficient and
convenient way to obtain suitable and highly proton-conducting materials
by attaching NH3 molecules.