Exfoliation and film preparation of a layered titanate, Na2Ti3O7, and intercalation of pseudoisocyanine dyeElectronic supplementary information (ESI) available: XRD patterns of (a) the starting material Na2Ti3O7, (b) H/Ti3O7, (c) MA/Ti3O7 and (d) PA/Ti3O7. See http://www.rsc.org/suppdata/jm/b3/b308800f/