Controlling Metal-Organic Structure by Tuning Molecular Size, Supported Substrate, and Type of Metal

Metal-organic structures are controllably prepared by tuning molecular size, supported substrates, and different kinds of metals. They are characterized by ultra-high vacuum low-temperature scanning tunnelling microscopy and Density functional theory calculations. The relatively larger size of all-trans-retinoic acid (ReA) compared to (2E,4E)-3-methyl-5-(2,6,6-trimethylcyclohex-1-enyl)penta-2,4-dienoic acid (DiA) leads to a bigger gap between neighboring ReA in a tetramer and allows for insertion of molecules, forming high density patterns. ReA forms various structures with different ratios (4:0, 3:1, 2:2) of the two chiral enantiomers on the less reactive Au(111) other than Ag(111). Unlike transition metals, electrostatic attraction between molecules and alkali metals is the origin of the formation of large quartet islands.