0000000000009444
AUTHOR
M. ÁNgeles Herranz
Mono- and Tripodal Porphyrins: Investigation on the Influence of the Number of Pyrene Anchors in Carbon Nanotube and Graphene Hybrids.
A series of molecular precursors, containing one (1 and 3) or three (2 and 4) pyrene anchors, covalently linked to porphyrins (free base or Zn), were prepared and characterized. All of them enable ...
The Role of Planarity versus Nonplanarity in the Electronic Communication of TCAQ-Based Push–Pull Chromophores
Donor-acceptor-substituted alkynes, endowed with 11,11,12,12-tetracyano-9,10-anthraquinodimethane (TCAQ) and N,N-dimethylaniline (DMA) units, have been further functionalized by a [2+2] cycloaddition with tetracyanoethylene (TCNE) followed by a subsequent retro-electrocyclization to form distorted nonplanar structures with bridging 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) units. Comprehensive spectroscopic, electrochemical, and computational studies have been carried out to compare the electronic communication in planar (alkyne bridges) and nonplanar (TCBD bridges) TCAQ-based push-pull chromophores. Cyclic voltammetry and UV/Vis absorption measurements confirm the electronic communication be…
Bowl-shape electron donors with absorptions in the visible range of the solar spectrum and their supramolecular assemblies with C 60
We describe the synthesis, electronic, optical and photophysical properties of a family of three electron-donor bowl-shaped organic molecules that absorb light in the whole range of the visible spectrum (up to 800 nm in one case), and associate C60 in solution with binding constants in the range of 104–102 M−1 as measured from both UV-vis and fluorescence titrations in several solvents. These molecules are π-extended derivatives of tetrathiafulvalene, based on a truxene core to which two or three units of dithiole are covalently attached. The inclusion of the bulky dithiole groups is responsible for their bowl-shape geometry, which allows them to associate with C60, and their electron-donor…
Carbon Nanostructures: Covalent and Macromolecular Chemistry
The aim of this introductory chapter is to bring to the attention of the readers the achievements made in the chemistry of carbon nanostructures and, mostly, in the chemistry of fullerenes, carbon nanotubes (CNTs), and the most recent graphenes. Since the discovery of fullerenes in 1985 and their further preparation in multigram amounts, the chemistry and reactivity of thesemolecular carbon allotropes have been well established. Actually, this chemical reactivity has been used as a benchmark for further studies carried out in the coming carbon nanotubes (single andmultiple wall) and graphenes. Assuming that the fundamental chemistry of fullerenes is known and basically corresponds to that o…
Aminopyrimidine-Based Donor–Acceptor Chromophores: Push–Pull versus Aromatic Behaviour
Novel 2-aminopyrimidines substituted with two electron-donor dialkylamino groups and either one dicyanovinyl (4a–d) or one tricyanovinyl (7a–d) electron-acceptor group have been synthesized, and the balance between their push–pull character and their aromatic behaviour has been studied by experimental (spectroscopic, electrochemical and X-ray analysis) and theoretical (DFT/B3LYP/6-31G**) methods. Calculations reveal that the push–pull character is energetically favoured with respect to the preservation of the aromaticity of the pyrimidine ring. X-ray analysis of 7a confirms the theoretical predictions and reveals a strong distortion from planarity due to the steric interaction between the t…
Synthesis and radical coupling of pyridine-bridged π-extended tetrathiafulvalene (TTF)-type donors and push–pull analogues
A new family of pi-extended TTF analogues (3a-c) and D-pi-A chromophores (5a-c), in which the electroactive units (1,3-dithiole rings and 2,2-dicyanovinyl groups) are connected through a pyridine bridge with a meta substitution pattern, is reported. The redox behavior of these compounds has been investigated by cyclic voltammetry and theoretical calculations performed at the B3P86/6-31G** level. Unlike many pi-extended TTF derivatives, the 1,3-dithiole rings in compounds 3a-c do not behave independently and two oxidation processes are observed with an anodic separation ranging from 50 to 150 mV. Calculations show that electrons are equally extracted from both dithiole rings. A biradical str…