Chemistry of water-soluble carbon nanotubes and carbon quantum dots with group IB metal-dithiolenes: structural and photophysical properties

Abstract

A series of nanostructures of transition-metal dithiolenes is prepared, and their interactions with CNTs and CQDs are investigated. Silver(I) and copper(II)dithiolenes [PPh₄]₃[{Ag(mnt)}₂I] (1) and [PPh₄]₂[Cu(mnt)₂]₂ (2) (mnt = maleonitriledithiolate) form nanospheres with diameters of 150 nm–270 nm and gold(III) dithiolene [PPh₄][Au(mnt)₂]₂ (3) forms doughnut-shaped nanoparticles with a diameter of 1.9 µm. The nanospheres of silver(I) dithiolene (1) interact with functionalized carbon nanotubes to form giant composite spheres (4) of diameter 10.3 µm, whereas f-CNTs uniquely tie up doughnut-shaped nanoparticles of gold dithiolene along the perimeter to form composite discs (5). The nanospheres (1) interact with carbon quantum dots, forming concave composite discs (7) filled with CQDs only at the central part. In the CQD-composite (8), gold(III) dithiolene interacts with water-soluble CQDs only along the perimeter. EDX analyses of the nanospheres, doughnut-shaped nanoparticles and composite spheres confirmed the presence of the expected elements and were consistent with the proposed formulae. The X-ray structure analysis of the gold(III) dithiolene (3) reveals a unique lattice packing feature with a chain structure of [Au(mnt)₂] anions encapsulating [PPh₄] cations. The pure nano-microspheres of (1) are imaged as concave luminescent spheres, whereas the f-CNT-composite spheres (4) and f-CQD composite spheres (7) are imaged as compact microspheres in the visible region.