Synthesis and characterization of a new layered compound of trimesic acidElectronic supplementary information (ESI) available: top view of the HxBTC anionic network (Fig. S1) and detailed hydrogen bond graph sets present in the interactions linking the two HxBTC sheets within a double layer (Fig. S2). See http://www.rsc.org/suppdata/nj/b1/b108083k/