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Salophens and Salens are Schiff bases generated through the condensation of two equivalents of salicylaldehyde with either 1,2-phenylenediamines or aliphatic diamines, respectively. Both ligands have been extensively exploited as key building blocks in coordination chemistry and catalysis. In particular, their metal complexes have been widely used for various catalytical transformations with high yield and selectivity. Through the modification of the phenol unit it is possible to tune the steric hindrance and electronic properties of Salophen and Salen. The introduction of long aliphatic chains in salicylaldehydes can be used to promote their self-assembly into ordered supramolecular structures on solid surfaces. Herein, we report a novel method towards the facile synthesis of robust and air-stable [Al(Salophen)] derivatives capable of undergoing spontaneous self-assembly at the graphite/solution interface forming highly-ordered nanopatterns. The new synthetic approach relies on the use of [MeAlIII (Salophen)] as a building unit to introduce, via a simple acid/base reaction with functionalized acidic phenol derivatives, selected frameworks integrating multiple functions for efficient surface decoration. STM imaging at the solid/liquid interface made it possible to monitor the formation of ordered supramolecular structures. In addition, the redox properties of the Salophen derivatives functionalized with ferrocene units in solution and on surface were unraveled by cyclic voltammetry. The use of a five-coordinate aluminum alkyl Salophen precursor enables the tailoring of new Salophen molecules capable of undergoing controlled self-assembly on HOPG, and thereby it can be exploited to introduce multiple functionalities with subnanometer precision at surfaces, ultimately forming ordered functional patterns.

The electrochemistry of a family of recently synthesized isoalloxazine cyclophanes containing anthraquinones, variously substituted and linked by aliphatic chains of different lengths, has been studied. The redox behavior of such species was elucidated by complementing the voltammetric studies with DFT molecular modelling. In these cyclophanes (mimicking the active centers of enzymes), the distance between chromophores and their reciprocal orientations were found to significantly modify their redox properties. Inter-moiety π−π stacking plays an important role in the electrochemical behavior by modulating the orbital energies, which leads to an inversion of the localization of the first reduction, with the anthraquinone being reduced before the more electron-accepting flavine.

Indium tin oxide (ITO) and silicon with a thermally grown SiO2 layer (Si/SiO2) substrates have been functionalized by ferrocene bound through Sn(O)x (x=2 or 3) linkers preliminarly grafted on the surface by reaction of the terminal hydroxyl groups with tetra(tert-butoxy)tin. The two steps modification of the surface was carried out by chemical vapour deposition metathesis reaction producing a self-assembled monolayer of ferrocene. The ITO and Si/SiO2 thus functionalized have been characterized by voltammetric, amperometric, electrochemical impedance spectroscopy and scanning probe microscopy techniques which assessed the formation of a stable and rather compact covalently bound ferrocenyl monolayer with improved electron transfer properties.

The synthesis of two A2B2 porphyrins, {5,15-bis-[4-(octyloxy)phenyl]-porphyrinato}zinc(II) (4) and {5,15-bis- (carbazol-3-yl-ethynyl)-10,20-bis-[4-(octyloxy)phenyl]-porphinato}-zinc(II) (9), is reported. Their photophysical properties were studied by steady-state absorption and emission. Substituting the carbazolylethynyl moieties at two of the meso positions results in a large bathochromic shift of all the absorption bands, a notable increase in the absorption coefficient of the Q(0,0) band, and higher fluorescence quantum yield compared to porphyrin 4, with two unsubstituted meso positions. Cyclic voltammetry and digital simulation show that electrogenerated radical ions of 9 are more stable than those of 4. The lack of substituents at the meso positions of 4 leads to dimerization reactions of the radical cation. Despite this, the annihilation reaction of 4 and 9 produces very similar electrogenerated chemiluminescence (ECL) intensity. Spectroelectrochemical experiments demonstrate that the electroreduction of 9 leads to a strong absorption band that might quench the ECL.