Self-assembled microtubes and rhodamine 6G functionalized Raman-active gold microrods from 1-hydroxybenzotriazole

RAVULA THIRUPATHI^a,b and ERODE N PRABHAKARAN^b,c,*

^aSolid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560 012, India

^bNanoscience Initiative, Indian Institute of Science, Bangalore, 560 012, India

^cDepartment of Organic Chemistry, Indian Institute of Science, Bangalore, 560 012, India

*Corresponding author. E-mail: eprabhak@orgchem.iisc.ernet.in; erodeprabhakaran@gmail.com

MS received 18 October 2010; revised 20 January 2011; accepted 4 February 2011

Abstract. 1-Hydroxybenzotriazole spontaneously self-assembles to form hollow, linear microtubes initiated by controlled evaporation from water. The tube cavities act as thermo-labile micromoulds for the synthesis of linear gold microrods. Rhodamine 6G-labelled gold microrods, exhibiting surface enhanced resonance Raman activity, have been synthesized using the HOBT microtubes.

Graphical Abstract. 1-Hydroxybenzotriazole spontaneously self-assembles into hollow, linear microtubes with high persistence lengths and monodisperse internal diameters. Tube formation occurs by the rolling of crystalline sheets of HOBT formed upon controlled evaporation of water from aqueous solutions. The hollow microtube cavities act as thermo-labile molds for casting gold nanoparticles and for the synthesis of linear rhodamine 6G-labelled gold microrods that exhibit fluorescence and surface enhanced Raman activity.

Keywords. Microtubes; gold microrods; self-assembly; Raman spectroscopy; 1-hydroxy benzotriazole.