An Alternate [2×2] Grid Constructed Around TiO4N2 Units |
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Authors: | Erin Day Brice Kauffmann Matthieu Scarpi-Luttenauer Alain Chaumont Marc Henry Pierre Mobian |
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Institution: | 1. Laboratoire de Chimie Moléculaire de l'Etat Solide, UMR 7140 UDS-CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67000 Strasbourg, France;2. Univ. Bordeaux, IECB, UMS 3033/US 001, 2 rue Robert Escarpit, 33607 Pessac, France;3. Laboratoire de Modélisation et Simulations Moléculaires, UMR 7140 UDS-CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67000 Strasbourg, France |
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Abstract: | The formation of a tetranuclear self-assembled species constructed around a TiO4N2 motif is reported. This aggregate is generated from Ti(OiPr)4, 2,2’-bipyrimidine (bpym) and a bis-biphenol strand (L2H4) where two 2,2’-biphenol units are connected with a biphenyl spacer. The solid-state structure of the Ti4(L2)4(bpym)4] architecture reveals the formation of an unprecedented chiral alternate 2×2] grid. In addition to the structural characterization of the Ti4(L2)4(bpym)4] architecture, geometry optimisation on various possible isomeric tetrameric assemblies (2×2] grid, alternate 2×2] grid, circular helicate or cyclic hemihelicate) is performed using DFT calculations. These results confirm the higher stability of the alternate 2×2] grid over the other possible tetranuclear isomers and allow examining the replacement of the bpym ligands by two novel diimine chelates within the tetranuclear assembly (2,2’-bipyridine=bipy and 2,2’-bipyrazine=bipyraz). From this initial theoretical investigation, the competition between these three nitrogen ligands in the course of the self-assembly process is next evaluated. Overall, this investigation shows that the exclusive formation of the alternate 2×2] grid is driven by CH⋅⋅⋅N interactions. |
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Keywords: | alternate grid CH⋅⋅⋅N interactions selection DFT calculations TiO4N2 |
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