Photoswitchable 11 nm CsCoFe Prussian Blue Analogue Nanocrystals with High Relaxation Temperature.
Photoswitchable 11 nm CsCoFe Prussian Blue Analogue Nanocrystals with High Relaxation Temperature.
复制标题
具有高弛豫温度的光开关 11 nm CsCoFe 普鲁士蓝类似纳米晶体。
作者：
Linh Trinh;S. Zerdane;S. Mazérat;N. Dia;D. Dragoe;C. Herrero;E. Rivière;L. Catala;M. Cammarata;E. Collet;T. Mallah
采用无模板法制备了具有Cs{Co[Fe(CN)6]}配位网络的11 nm光开关纳米晶体。纳米晶体从胶体溶液中被十六烷基三甲基铵（CTA）阳离子包裹或包埋在有机聚合物聚乙烯吡咯烷酮（PVP）中。互补磁、光谱和结构技术，包括EPR光谱，揭示了大多数（~ 70%）的低自旋和光活性抗磁性CoIIIFeII对位于纳米晶体的核心，CoIIFeII和CoIIFeIII的混合物主要存在于物体的外壳内。虽然具有相似空位浓度的大块化合物没有表现出明显的光诱导电荷转移，但观察到的纳米晶体的光活性归因于它们的纳米尺寸。当PVP被CTA取代时，光诱导态的弛豫温度上升了约55 K。这是由于致密的CsCoFe_CTA材料具有较大的刚性，其亚稳态低于CsCoFe_PVP，导致较大的弛豫能垒，从而获得较高的弛豫温度。
Photoswitchable 11 nm nanocrystals with the coordination network Cs{Co[Fe(CN)6]} were obtained using a template-free method. The nanocrystals were recovered from the colloidal solutions as solid materials surrounded by cetyltrimethylammonium (CTA) cations or embedded in the organic polymer polyvinylpyrrolidone (PVP). Complementary magnetic, spectroscopic, and structural techniques, including EPR spectroscopy, reveal a majority (∼70%) of the low-spin and photoactive diamagnetic CoIIIFeII pairs located in the core of the nanocrystals and a mixture of CoIIFeII and CoIIFeIII species present mainly within the shell of the objects. While bulk compounds with similar vacancy concentration do not exhibit noticeable photoinduced charge transfer, the observed photoactivity of the nanocrystals is ascribed to their nanometric size. The relaxation temperature of the photoinduced state shifts upward by ∼55 K when PVP is replaced by CTA. This is ascribed to the larger rigidity of the dense CsCoFe_CTA material, whose metastable state is lower than that for CsCoFe_PVP, leading to a larger relaxation energy barrier and, therefore, to a higher relaxation temperature.