Insulated conjugated bimetallopolymer with sigmoidal response by dual self-controlling system as a biomimetic material

Biological systems are known to spontaneously adjust the functioning of neurotransmitters, ion channels, and the immune system, being promoted or regulated through allosteric effects or inhibitors, affording non-linear responses to external stimuli. Here we report that an insulated conjugated bimetallopolymer, in which Ru(II) and Pt(II) complexes are mutually connected with insulated conjugations, exhibits phosphorescence in response to CO gas. The net profile corresponds to a sigmoidal response with a dual self-controlling system, where drastic changes were exhibited at two threshold concentrations. The first threshold for activation of the system is triggered by the depolymerization of the non-radiative conjugated polymer to luminescent monomers, while the second one for regulation is triggered by the switch in the rate-determining step of the Ru complex. Such a molecular design with cooperative multiple transition metals would provide routes for the development of higher-ordered artificial molecular systems bearing bioinspired responses with autonomous modulation.


Synthesis of 2
Under argon, 1 (189 mg, 117 mol), PdCl2 (PPh3)2 (4.2 mg, 5.9 mol) and CuI (1.1 mg, 5.9 mol) were added into degassed piperidine (2.5 mL). Into the solution, trimethylsilylacetylene (80.8 L, 569 mol) was added, and then the reaction mixture was stirred at room temperature for 18 h. The mixture was quenched with aqueous NH4Cl and diluted with CHCl3. The organic layer was separated and dried over MgSO4, and then filtered. The solvent was removed by evaporation, and the residue was purified by GPC with CHCl3 as the eluent to yield 1 as a yellow solid (192 mg, quant.).

Synthesis of 3
Under argon, 2 (150 mg, 94.7 mol) and K2CO3 (39.1 mg, 283 mol) were dissolved in MeOH (20 mL). The reaction mixture was stirred at room temperature for 1 h. The mixture was quenched with H2O, and diluted with CHCl3 and washed with brine. The organic layer was separated and dried over
The reaction mixture was irradiated using a high-pressure mercury lamp for 22 h under argon bubbling and stirring at room temperature. As the reaction was proceeded, the solution color was changed from red to purple. The solvent was removed by evaporation and the residue was purified by GPC with CHCl3 as the eluent to yield S1 as a purple solid (97 mg, 78%).
Under an argon, S1 (85.0 mg, 22.0 mol) and K2CO3 (11.8 mg, 85.5 mol) was dissolved in MeOH (3 mL) and THF (15 mL). The reaction mixture was stirred at room temperature for 3.5 h. The mixture was quenched with H2O, and diluted with CHCl3 and washed with brine. The organic layer was separated and dried over MgSO4. The solvent was removed by evaporation and the residue was purified by GPC with CHCl3 as the eluent to yield S2 as a purple solid (63 mg, 77% Under argon, S2 (12 mg, 3.0 mol) and trans-PtCl2 (PEt3)2 (1.5 mg, 3.0 mol) and CuI (0.06 mg, 0.3 mol) were dissolved in degassed piperidine (2 mL). The reaction mixture was stirred at room temperature for 5 h. The mixture was quenched with aqueous NH4Cl and diluted with CHCl3. The organic layer was separated and dried over MgSO4, and then filtered. The solvent was removed by evaporation, and the residue (Mw = 5.510 4 , Mn = 2.410 4 ) was purified by GPC with CHCl3 as the eluent to yield 6 as a purple solid (10 mg, 78%). Spectra were in good agreement with that mentioned above.

Supplementary Note 2 Chemical shift in rotaxane structure
Insulated (4) and uninsulated (4′) Pt complexes indicated their characteristic chemical shifts in aromatic region of 1 H NMR spectra according to their supramolecular structures. The 1 H NMR spectrum of 4 displayed low-field shift in the insulated aryl groups and high-field shift in the pyridyl groups as compared to that of 4′ ( Supplementary Fig. 1). The shifts attributed to supramolecular interaction between PM -CDs and phenyl groups and to neighboring effect between the lops of PM  Absorption spectra of bimetallopolymer 6 for various concentrations ranging from 3.3 × 10 -3 mg/mL to 5.0 × 10 -2 mg/mL and their maximum absorption wavelengths were independent of the diluted solution concentrations Supplementary Fig. 8). The results indicated that the bimetallopolymer did not form any assembled structures for diluted solution concentrations during our experiments. As shown in Supplementary Fig. 10b, bimetallopolymer successfully depolymerized to monomers 4 and 5 after the reaction with CO gas. Similarly, analysis with 254 nm detector indicated that Ru porphyrin 5 was successfully generated in the reaction mixture ( Supplementary Fig. 10d). Subsequent UV irradiation provided repolymerizing bimetallopolymer 6 along with consuming the monomers as shown in Supplementary Fig. 10c. While the polymerization degree after repolymerization were slightly less than that before depolymerization, these results demonstrated that the reaction with CO e h c f S16 A mixed gas experiment was conducted by using ambient air (a mixture of N2, O2, and CO2) as one of the mixed gases. The bimetallopolymer 6 responded to 1% CO gas under mixed gas with ambient air to display phosphorescence (Supplementary Fig. 12 and 13). The results indicated that the responsiveness of the bimetallopolymer to CO gas was not affected even under the mixed gas condition.  The calculated structure of 4 shown in Supplementary Fig. 2 was determined by ONIOM [4][5][6] calculations. In the calculation, the molecular system was divided into two layers above C (sp 2 )-O bonds. The high layers were assigned to the conjugated backbones, involving the phenylene ethynylene moieties and the Pt complex, for B3LYP/Lanl2DZ calculation. The low layers containing PM -CD parts were calculated on semi-empirical molecular orbital calculation using PM6 method.

Supplementary
All calculations were performed with the Gaussian 09. 7