**5.2 Atomic force microscopy (AFM)**

The morphology of the polymers can be observed directly onto ITO electrodes by atomic force microscopy (AFM).

Depending on the solvent used to wash the electrode, the morphologies of the deposited polymers appear different (Ruhlmann et al., 2008). Indeed, when water is used to wash the polymer obtained from the mono-substituted porphyrin ZnOEP(bpy)+, this one appears in the form of coils (diameter of *ca.* 50 nm) quasi-packed in the same direction (Fig. 11.a). This orientation effect might be induced by a self-alignment of the polycationic coils in the applied electric field during the electropolymerization. Moreover, after changing of the position of the ITO electrode, the coils cross over each, as shown in Fig. 11.a. That demonstrates the direct influence of the applied electric field onto the polymer arrangement during the electropolymerization process. Nevertheless, when CH3CN is used instead of water to wash the polymer, a drastic reorganization of these tightly packed coils is observed. Indeed, the alignment of the polymers disappears and a homogeneous dispersion of the coils is observed (Fig. 11.b).

Fig. 11. Atomic force micrographs of different polymers obtained onto ITO electrodes after 25 iterative scans: (a) and (b) polymer obtained from ZnOEP(bpy)+, after washing with (a) water and (b) CH3CN; (c) and (d) polymer obtained from ZnOEP(bpy)22+, after washing with (c) water and (d) CH3CN; (e) and (f) polymer obtained from ZnOEP + bpy, after washing with (e) water and (f) CH3CN (zoom).

Moreover, the polymers can be removed from the electrode by dissolution in dimethylformamide (DMF). That allows to record the spectra of the polymers in solution (red spectrum, Fig. 10.a). Comparing the spectra obtained onto ITO electrodes, the red-shift of the Soret band for spectra recorded in solution appears smaller. Such an evolution can be explained by a decrease of the interactions between the macrocycles when the polymers are

When polymers are in solution, it is also possible to study their luminescence properties: all

The morphology of the polymers can be observed directly onto ITO electrodes by atomic

Depending on the solvent used to wash the electrode, the morphologies of the deposited polymers appear different (Ruhlmann et al., 2008). Indeed, when water is used to wash the polymer obtained from the mono-substituted porphyrin ZnOEP(bpy)+, this one appears in the form of coils (diameter of *ca.* 50 nm) quasi-packed in the same direction (Fig. 11.a). This orientation effect might be induced by a self-alignment of the polycationic coils in the applied electric field during the electropolymerization. Moreover, after changing of the position of the ITO electrode, the coils cross over each, as shown in Fig. 11.a. That demonstrates the direct influence of the applied electric field onto the polymer arrangement during the electropolymerization process. Nevertheless, when CH3CN is used instead of water to wash the polymer, a drastic reorganization of these tightly packed coils is observed. Indeed, the alignment of the polymers disappears and a homogeneous dispersion of the

Fig. 11. Atomic force micrographs of different polymers obtained onto ITO electrodes after 25 iterative scans: (a) and (b) polymer obtained from ZnOEP(bpy)+, after washing with (a) water and (b) CH3CN; (c) and (d) polymer obtained from ZnOEP(bpy)22+, after washing with (c) water and (d) CH3CN; (e) and (f) polymer obtained from ZnOEP + bpy, after

in solution. Indeed, in solution, polymeric chains are partially unfolded.

the investigated polymers show a total quenching (Fig. 10.b).

**5.2 Atomic force microscopy (AFM)** 

force microscopy (AFM).

coils is observed (Fig. 11.b).

washing with (e) water and (f) CH3CN (zoom).

It can be noticed that similar electropolymerization has also been performed from the ZnOEP macrocycles substituted by two bipyridinium groups in *cis*-position (zinc 5,10-dibipyridiniumβ-octaethylporphyrin, abbreviated 5,10-ZnOEP(bpy)22+) (Ruhlmann et al., 2008). In that case, a regular arrangement of the coils aggregated in the form of "peanuts" (width of *ca.* 100 nm and length of *ca.* 900 nm), all oriented in the same direction, is observed when the washing is performed with water (Fig. 11.c). This enhancement of the self-alignment of the coils induced by the applied electric field could be explained by the increase of the number of positive charges in this case (because of the presence of two bipyridinium substituents onto each macrocycle) which would induce stronger coulombic repulsions between the different subunits. However a treatment with CH3CN induces also a homogeneous dispersion of the coils (Fig. 11.d) as previously observed for the polymer obtained from the mono-substituted ZnOEP(bpy)+.

In the case of the polymer obtained from the non-substituted ZnOEP with free bpy, tightly packed coils are also observed, but without specific alignment (Giraudeau et al., 2010), whatever the solvent used to wash the electrode (Fig. 11.e and f). That can be tentatively explained by the presence of free bpy which could lead to a disorganization of the film. Moreover, the free bpy can also axially coordinate the Zn central metal of the macrocycles (Giraudeau et al., 2010) which increases the distance between the macrocycles and consequently could lead to a decrease of the electrostatic effect between the macrocycles. As a result, effect of the applied electric field should be lesser onto the electropolymerization process, the orientation effect disappearing in this case.
