Self-organization processes allow the spontaneous but controlled generation of complex organic or inorganic architecture on the basis of the molecular information stored in the components, and its processing through the interactional algorithms defined by specific molecular recognition events. [1, 2] Such processes connect input components with output entity(ies), with a fidelity/reliability depending on the robustness of the program, that is, its ability to resist interference from factors other than the directing/dominant coding interactions.
While in equilibrium conditions, the process ideally leads to the preferential formation of a given entity under thermodynamic control/pressure; input and output species may be linked by complex mechanistic pathways and involve the generation of kinetic species that may or may not be direct intermediates. Such is the case, for instance, in the final formation of the thermodynamically favored circular helicates following kinetically favored triple-helical complexes. [3] Although it is crucial to gain insight into the mechanistic, thermodynamic, and kinetic features of the self-organization process, only few such studies have been reported. [4] Whereas the preferential, ideally exclusive, formation of a given entity is usually pursued, various factors may interfere with the dominant code and complicate the issue. Thus, considering the self-assembly of inorganic grid architectures, which makes use of specifically designed ligands and of strong metal-ion coordination interactions, [2 Γ 2]-, [5] [3 Γ 3]-, [6] and [4 Γ 4]- [7] type entities form exclusively. However, with a pentadentate ligand, both an incomplete [4 Γ 5]Ag 20 grid and a quadruple helicate are simultaneously generated in place of the full [5 Γ 5]Ag 25 entity, because of the interplay of various structural factors. [8] On the other hand, such cases also stress that when different β’Boltzmann speciesβ« are thus formed, provided they are well defined, diversity ensues, an attractive feature of multiple outputs [9] in a self-assembly process. To gain understanding of the self-organization pathways, it is first necessary to identify the species that may form and then try to define their role in the process. In particular, features such as 197 (2), 183 (1), 169 (1), 157, (1), 143 (47), 128 (28), 117 (7), 104 (2), 91 (13), 77 (5), 57 (100), 41 (57).
Method B: Under an argon atmosphere, a mixture of zinc dust (0.85 g, 13 mmol), 1,2-dibromoethane (0.19 g, 1.0 mmol), and THF (2 mL) was heated in a three-necked flask to 60 Β± 70 8C for 2 Β± 3 min and then cooled to room temperature. Chlorotrimethylsilane (0.1 mL) was added, and the mixture was stirred at room temperature for 15 min. A solution of RI (12 mmol) in THF (10 mL) was then added, and the mixture was stirred for 12 h at 35 8C. The resulting RZnI solution was then added to another threenecked flask, in which [NiCl 2 (PPh 3 ) 2 ] (0.2 g, 0.3 mmol) and THF (2 mL) had been previously heated at 60 8C for 2 min. The resulting mixture was cooled to Γ 18 8C. A solution of aldehyde (10 mmol) and chlorotrimethylsilane (20 mmol) in THF (10 mL) was added over a few minutes and the mixture was allowed to warm to room temperature. After stirring the mixture for 12 h, saturated aqueous solution of NH 4 Cl (10 mL) and Et 2 O (10 mL) were added and the mixture was stirred for 10 min. The organic layer was separated, dried over anhydrous MgSO 4 , and concentrated. The product was isolated from the crude reaction mixture by column chromatography on silica gel using petroleum ether/ethyl acetate as the eluent.