www.afm-journal.de FULL PAPER www.MaterialsViews.com © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 667 wileyonlinelibrary.com Adv. Funct. Mater. 2011, 21, 667–673 Supratim Basak and Rajadurai Chandrasekar* 1. Introduction Luminescent organic nanotubes are of great importance as a building blocks in future miniaturized devices. [1,9b] With the rapid advancement of nanoelectronics, one-dimensional lumi- nescent nanotubular structures have attracted particular interest because of their unique optoelectronic properties due to a two- dimensional quantum confinement effect. [1] Untill now, most of the known luminescent nanotubular structures are purely organic in nature and display only single-color emission. Nano- fabrication of multicolor-emitting hybrid nanotubular mate- rials from two different soft matters (organic/inorganic) is an unexplored and sophisticated research area of nanoscience and technology. Successful groundwork in this area could lead to new hybrid nanotubular luminogens, capable of performing a sensing, photonic, biological, or trans- port function. However, the controlled and selective fabrication of hybrid nano- tubes with multicolor emission requires a rational design and step-wise preparation strategy at the nanoscale for a successful integration into nanofunctional devices. Controlling and understanding the growth [2] of an organic soft matter into a shape-defined nanotubular configuration (cylindrical, hexagonal, rectangular, and parallelogrammatic) is itself a challenging area. Untill now, most of the organic nano/submicrotubes fabricated from the self-assembly of disclike molecules, [3] den- drimers, [4] amphiphiles, [5] small organic molecules, [6] peptides, [7] and polymers [8] are all of single-component nature, and shape control at the nanoscale has been achieved by using crystallization, template synthesis, vaporization, and amphiphilic assembly techniques. It has been recently recognized that, apart from supramo- lecular interactions [2–9] (van der Waals interactions, hydrogen bonding, coordination, and π – π stacking), the solubility of molecular building blocks in organic solvents and their con- centration also play a crucial role in controlling the shape, size, and texture of the organic nanostructures. [6,9b] To fabricate multi- functional organic/inorganic hybrid nanotubular structures, the use of small organic ligand molecules as nanobricks is a logical approach, since it provides easy structural tunability and diversity, which are important to control their solubility as well as their molecular function at the nanoscale. Additionally the ligand molecules available on the surface of the shape-defined primary nano-superstructure can also be effectively utilized to perform coordination chemistry with different metal ions (surface modification) at the solid/liquid interface. This meth- odology may form pre-shape-instructed secondary inorganic nanostructures on the primary organic nano-superstructure with multifunctional properties. Based on this idea, we have fab- ricated a tricolor luminescence parallepipedic organic/inorganic nanostructure via a step-wise self-assembly approach starting from ligand 1 ( Figure 1). Herein, we report our one-pot and two-step nanofabrication approach ( Scheme 1 ): i) fabrication of several-micrometer-long Multiluminescent Hybrid Organic/Inorganic Nanotubular Structures: One-Pot Fabrication of Tricolor (Blue–Red–Purple) Luminescent Parallepipedic Organic Superstructure Grafted with Europium Complexes DOI: 10.1002/adfm.201002270 This article focuses on an innovative one-pot fabrication of organic/inorganic hybrid parallepipedic tubes with rectangular cavities displaying multicolor luminescence. Firstly, using a novel back-to-back coupled 2,6-di-pyrazol-1- ylpyridine ligand, blue-emitting several-micrometer-long (ca. 50 μm) paralle- pipedic organic nanotubes with rectangular cavities were fabricated in THF/ water via supramolecular (H-bonding and π π – π π stacking) and solvent-assisted self-assembly. Secondly, in the same pot, the ligand molecules available on the surface of the ligand nanotubes were reacted with Eu(tta) 3 molecules at the solid/liquid interface to form a layer of red-emitting Eu(III) complex coating on the inner and outer surface of the tubes. The resultant organic/ inorganic hybrid parallepipedic nanotubes fabricated using this novel bottom-up one-pot technique display tricolor (blue–red–purple) lumines- cence, i.e., blue and red dual emission from the organic ligand and the Eu(III) complex, respectively, and a purple color due to the mixing of the two colors. This simple technique signifies an innovative and important method in the development of bottom-up nanotechnology of multiluminescent organic/ inorganic hybrid nanotubes. Prof. R. Chandrasekar, S. Basak School of Chemistry University of Hyderabad Prof. C. R. Rao Road, Gachi Bowli, Hyderabad – 500 046, India E-mail: rcsc@uohyd.ernet.in; chandrasekar100@yahoo.com