TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: Linkage is between carbonyl oxygen of the carbon nanotube and nanocrystal, between the carbonyl carbon of the carbon nanotube and functional group on the nanocrystal, or between carbonyl carbon of the carbon nanotube and functional group on a linker attached to the nanocrystal. The nanocrystal is transition metal chalcogenide. The transition metal chalcogenide nanocrystal is wurtzite cadmium selenide, cadmium sulfide, cadmium telluride, zinc selenide, or zinc sulfide. The transition metal chalcogenide nanocrystal is mercury sulfide, mercury selenide, mercury telluride, or zinc telluride. The nanocrystal is gallium arsenide, indium gallium arsenide, indium phosphide, indium arsenide, germanium, or silicon. The nanocrystal is metal oxide, preferably titanium dioxide. The metal oxide can also be zirconium oxide, aluminum oxide, iron, oxide, or ruthenium oxide. The nanocrystal is colloidal elemental metal. The colloidal elemental metal is gold, silver, platinum, or copper. The nanocrystal can also be nanobimetallic dispersion. The nanobimetallic dispersion is silver/iridium, platinum/gold, silver/palladium, platinum/palladium, nickel/palladium, or platinum/ruthenium. The covalent linkage is formed between carbonyl carbon of nanotube and amide group attached to the nanocrystal. The amine group is directly attached to the nanocrystal. The amine group is directly attached to the nanocrystal. The amine group is part of organic molecules linker. The linker comprises less than 20 C atoms. The organic molecule linker is bifunctional amine. The bifunctional amine is alkyl or aryl diamine derivative. The diamine derivative is ethylene diamine or semicarbazide. The carbon nanotube is single or multi-walled. The carbon nanotube is semi-conductor or metal. The nanocrystal is semiconductor. The end of the carbon nanotube is open. The nanotube is oxidized. The transitional metal chalcogenide nanocrystal has acid terminal group before linking to the nanotube. The thiol ligand is bifunctional legend containing acid and thiol-terminated moieties. The bifunctional ligand is p-mercaptobenzoic acid, thioglycolic acid, or 3-mercaptopropionic acid. The acid terminal group on the nanocrystal is converted into an amide before linking with the nanotube. A carboxylic group on the nanotube is converted into an amide before linking with nanocrystal. The nanotube and transition metal chalcogenide nanocrystal are linked by organic molecule linker in the presence of carbodiimide reagent. The carbon diimide reagent is 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, or N,N'-dicyclohexyl carbodiimide. The acid terminated transition metal chalcogenide nanocrystal is reacted with ammonium hydroxide to form amine-terminated transition metal chalcogenide nanocrystal before linking with carbonyl carbon of nanotube. The amine-terminated nanotube and amine-terminated nanocrystal are linked by dicarboxylic acid in the presence of carbodiimide reagent. The metal oxide is formed in the presence of amine-derivatized acid to form metal oxide nanocrystal bearing pendant amine groups on its surface, and reacting the oxidized nanotube with amine group bearing-nanocrystal in the presence of carbodiimide reagent. A titanium dioxide nanocrystal is made in the presence of amine terminated aliphatic carboxylic acid to form titanium dioxide nanocrystal bearing pendant amine groups, and reacting oxidized nanotube with amine group bearing nanocrystal in the presence of carbodiimide reagent. The amine terminated aliphatic carboxylic acid is 11-aminoundecanoic acid. The metal oxide nanocrystal is reacted with oxidized nanotube. Preferred Properties: The diameter of the single-walled and multi-walled carbon nanotube is 0.7-2.5nm and 3-30 nm, respectively. The particle size of the nanocrystal is 1-20. Preferred Methods: The method also comprises shortening the oxidized nanotube by acid etching, ion beam milling, ball milling, or gas etching. The acid-terminated transition metal chalcogenide nanocrystal is made by capping transition metal chalcogenide with trioctylphosphoine oxide (TOPO), and substituting the TOPO cap with thiol ligand to form acid-terminated transition metal chalcogenide nanocrystal. The acid terminal group on the nanocrystal is converted into an amide by reacting nanocrystal with bifunctional amine. A carboxylic group on the nanotube is converted into an amide by reacting the nanocrystal with bifunctional amine. The modification of conductance is tunability in conductance. The structural property is elasticity, mechanical properties, or ease of composite formation. The detection is through microscopy or micro-spectroscopy. The diameter of the rope is 2.5-250 nm. The diameter of the bundle is 2.5-250 nm.