Semi-insulating behaviour of self-assembled tin(iv)corrole nanospheres

Abstract

Three novel tin(iv)corrole complexes have been prepared and characterized by various spectroscopic techniques including single crystal X-ray structural analysis. Packing diagrams of the tin(iv)corroles revealed that corrolato-tin(iv)-chloride molecules are interconnected by intermolecular C-HCl hydrogen bonding interactions. HCl distances are 2.848 Å, 3.051 Å, and 2.915 Å, respectively, for the complexes. In addition, the C-HCl angles are 119.72°, 144.70°, and 147.08°, respectively, for the complexes. It was also observed that in one of the three synthesized complexes dimers were formed, while in the other two cases 1D infinite polymer chains were formed. Well-defined and nicely organized three-dimensional hollow nanospheres (SEM images on silicon wafers) with diameters of ca. 676 nm and 661 nm are obtained in the complexes, forming 1D polymer chains. By applying a thin layer of tin(iv)corrole nanospheres to an ITO surface (AFM height images of ITO films; ∼200 nm in height), a device was fabricated with the following composition: Ag/ITO-coated glass/tin(iv)corrole nanospheres/ITO-coated glass/Ag. The resistivity (ρ) of the nanostructured film was calculated to be ∼2.4 × 10(8) Ω cm, which falls in the range of semi-insulating semiconductors. CAFM current maps at 10 V bias show bright spots with a 10-20 pA intensity and indicate that the nanospheres (∼250 nm in diameter) are the electron-conducting pathway in the device. The semi-insulating behavior arises from the non-facile electron transfer in the HOMOs of the tin(iv)corrole nanospheres.

Electronic Structure of Corrole Derivatives: Insights from Molecular Structures, Spectroscopy, Electrochemistry, and Quantum Chemical Calculations

“…81 Similar emission characteristics have also been reported for SnCl triarylcorrole derivatives. 80 The aforementioned organotin corroles exhibit reversible oneelectron reduction at low reduction potentials < −1.0 V and high electrochemical HOMO−LUMO gaps of ∼2.05 V (Figure 34), all consistent with corrole-centered redox processes. 81 Both the first oxidation and the reduction potentials of Sn[OEC]Cl are about 0.3 V positively shifted relative to Sn[OEC]Ph.…”

“…A series of organotin Sn­[TPFPC]­(R) (R = alkyl or aryl) derivatives reported by Churchill and co-workers exhibits emission maxima of 608–616 nm, fluorescence quantum yields of (4.0–7.9) × 10 –3 , and lifetimes of 0.3–0.4 ns . Similar emission characteristics have also been reported for SnCl triarylcorrole derivatives …”

“…Tin corroles exhibit rather long M−N distances of 2.04−2.09 Å and domed geometries with M−N 4 displacements of 0.6−0.8 Å, consistent with the long covalent radius of tin (Sn 1.40 Å, Ge 1.2 Å). 79,80 Six-coordinate Sn corroles, which would require an essentially in-plane tin, are unknown. Like other innocent corrole derivatives, Sn corroles exhibit sharp Soret and Q bands (Figure 33).…”

Formation and Study of Nanostructured M-Monolayers and LS-Films of Triphenylcorrole

“…) to the surface of bi-distilled water with microliter syringes (1,10,20, and 100 µl, "Hamilton", Sweden) at the temperature of 20 ± 1 °C. The layers were compressed at the speed of 2.3 cm 2 ·min -1 15 minutes after the solution had been applied to the water surface.…”

“…[3][4][5][6][7][8][9] This property accounts for the compounds' high catalytic activity. [10] One of today's emerging trends is focused on creation of thin-film organic materials, including based on corroles, [11][12][13][14][15][16][17][18][19][20] especially those, where structural and functional units are represented by 2D and 3D nanoparticles. [21,22] First supermolecules of macroheterocyclic compounds were obtained.…”