Polyphenylene dendrimer-templated in situ construction of inorganic-organic hybrid rice-shaped Architectures

A novel dendrimer-templating method for the synthesis of CuO nanoparticles and the in situ construction of ordered inorganic-organic CuO-G2Td(COOH) ₁₆ rice-shaped architectures (RSAs) with analogous monocrystalline structures are reported. The primary CuO nanoparticles are linked by the G2Td(COOH)₁₆ dendrimer. This method provides a way to preserve the original properties of primary CuO nanoparticles in the ordered hybrid nanomaterials by using the 3D rigid polyphenylene dendrimer (G2Td(COOH) ₁₆) as a space isolation. The primary CuO nanoparticles with diameter of (6.3 ± 0.4) nm are synthesized via four successive reaction steps starting from the rapid reduction of Cu(NO₃)₂ by using NaBH₄ as reducer and G2Td(COOH)₁₆ as surfactant. The obtained hybrid CuOG2Td(COOH)₁₆ RSA, formed in the last reaction step, possesses a crystal structure analogous to a monocrystal as observed by transmission electron microscopy(TEM). In particular, the formation process of the RSA Is monitored by UV-vis, TEM, and X-ray diffraction. Small angle X-ray scattering and Fourier transform infrared spectroscopy are used to investigate the role of the dendrimer In the RSA formation process. The obtained results illuminate that Cu²⁺-COO coordination bonds play an indispensable role in bridging and dispersing the primary CuO nanoparticles to induce and maintain the hybrid RSA. More importantly, the RSA is retained through the Cu²⁺-COO^- coordination bonds even with HCl treatment, suggesting that the dendrlmers and Cu²⁺ ions may form rice-shaped polymeric complexes which could template the assembly of CuO nanoparticles towards RSAs. This study highlights the feasibility and flexibility of employing the peculiar dendrlmers to in-situ build up hybrid architectures which could further serve as templates, containers or nanoreactors for the synthesis of other nanomaterials.