Fluorescent asymmetrically cobalt-tipped CdSe@CdS core@shell nanorod heterostructures exhibiting room-temperature ferromagnetic behavior

J Am Chem Soc. 2009 Sep 9;131(35):12817-28. doi: 10.1021/ja904493c.

Abstract

A colloidal two-step seeded-growth approach has been devised to selectively synthesize three-component magnetic/semiconductor hybrid nanocrystals (HNCs) with a matchstick-like profile and tunable geometric parameters. The newly developed heterostructures individually comprise a single metallic Co head connected to either apexes of one rod-shaped section made of a CdSe core eccentrically embedded in a CdS shell. The specific topological arrangement realized arises from the peculiar anisotropic reactivity of the noncentrosymmetric CdSe@CdS core@shell nanorods that have been used as substrates to seed heterogeneous nucleation of Co in a surfactant-free environment from an organometallic precursor. The HNCs retain appreciable fluorescent emission in spite of photoexcited charge transfer from the semiconductor to the metal domain and exhibit unusual ferromagnetic-like behavior at room temperature.