Billing David G, Lemmerer Andreas
Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa.
Acta Crystallogr B. 2007 Oct;63(Pt 5):735-47. doi: 10.1107/S0108768107031758. Epub 2007 Sep 14.
Three inorganic-organic layered perovskite-type hybrids of the general formula [(C(n)H(2n+1)NH(3))(2)PbI(4)], n = 4, 5 and 6, display a number of reversible first-order phase transitions in the temperature range from 256 to 393 K. [(C(4)H(9)NH(3))(2)PbI(4)] has a single phase transition, [(C(5)H(11)NH(3))(2)PbI(4)] has two phase transitions and [(C(6)H(13)NH(3))(2)PbI(4)] has three phase transitions. In all three cases, the lowest-temperature phase transition is thermochromic and the crystals change colour from yellow in their lowest-temperature phase to orange in their higher-temperature phase for [(C(4)H(9)NH(3))(2)PbI(4)] and [(C(6)H(13)NH(3))(2)PbI(4)], and from orange to red for [(C(5)H(11)NH(3))(2)PbI(4)]. The structural details associated with this phase transition have been investigated via single-crystal X-ray diffraction, SC-XRD, for all three compounds.
三种通式为[(C(n)H(2n + 1)NH(3))(2)PbI(4)]（n = 4、5和6）的无机-有机层状钙钛矿型杂化物在256至393 K的温度范围内呈现出许多可逆的一级相变。[(C(4)H(9)NH(3))(2)PbI(4)]有一个相变，[(C(5)H(11)NH(3))(2)PbI(4)]有两个相变，[(C(6)H(13)NH(3))(2)PbI(4)]有三个相变。在所有三种情况下，最低温度的相变都是热致变色的，对于[(C(4)H(9)NH(3))(2)PbI(4)]和[(C(6)H(13)NH(3))(2)PbI(4)]，晶体在最低温度相时为黄色，在较高温度相时变为橙色，而对于[(C(5)H(11)NH(3))(2)PbI(4)]，则从橙色变为红色。已通过单晶X射线衍射（SC-XRD）对所有这三种化合物研究了与该相变相关的结构细节。
