Conjugated polymers are increasingly used as organic mixed ionic–electronic conductors in electrochemical applications for neuromorphic computing, bioelectronics, and energy harvesting. The design of efficient electrochemical devices relies on large modulations of the polymer conductivity, fast doping/dedoping kinetics, and high ionic uptake. In this work, structure–property relations are established and control of these parameters by the co‐existence of order and disorder in the phase morphology is demonstrated. Using in situ time‐resolved spectroelectrochemistry, resonant Raman, and terahertz (THz) conductivity measurements, the electrochemical doping in the different morphological domains of poly(3‐hexylthiophene) (P3HT) is investigated. The main finding is that bipolarons are found preferentially in disordered polymer regions, where they are formed faster and are thermodynamically more favored. On the other hand, polarons show a preference for ordered domains, leading to drastically different bipolaron/polaron ratios and doping/dedoping dynamics in the distinct regions. A significant enhancement of the electronic conductivity is evident when bipolarons start forming in the disordered regions, while the presence of bipolarons in the ordered regions is detrimental for transport. This study provides significant advances in the understanding of the impact of morphology on the electrochemical doping of conjugated polymers and the induced increase in conductivity.

Eight novel carbohydrate-tethered trithiolato dinuclear ruthenium(II)-arene complexes were synthesized using CuAAC ‘click’ (Cu(I)-catalyzed azide-alkyne cycloaddition) reactions, and there in vitro activity against transgenic T. gondii tachyzoites constitutively expressing β-galactosidase (T. gondii β-gal) and in non-infected human foreskin fibroblasts, HFF, was determined at 0.1 and 1 µM. When evaluated at 1 µM, seven diruthenium-carbohydrate conjugates strongly impaired parasite proliferation by >90%, while HFF viability was retained at 50% or more, and they were further subjected to the half-maximal inhibitory concentration (IC50) measurement on T. gondii β-gal. Results revealed that the biological activity of the hybrids was influenced both by the nature of the carbohydrate (glucose vs galactose) appended on ruthenium complex and the type/length of the linker between the two units. 23 and 26, two galactose-based diruthenium conjugates, exhibited low IC50 values and reduced effect on HFF viability when applied at 2.5 µM (23: IC50 = 0.032 µM/HFF viability 92% and 26: IC50 = 0.153 µM/HFF viability 97%). Remarkably, compounds 23 and 26 performed significantly better than the corresponding carbohydrate non-modified diruthenium complexes, showing that this type of conjugates are a promising approach for obtaining new antiparasitic compounds with reduced toxicity.

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Eight novel carbohydrate-tethered trithiolato dinuclear ruthenium(II)-arene complexes were synthesized using CuAAC 'click' (Cu(I)-catalyzed azide-alkyne cycloaddition) reactions and, together with the diruthenium intermediates, were assessed for their in vitro activity against transgenic Toxoplasma gondii (T. gondii) tachyzoites constitutively expressing β-galactosidase (T. gondii β-gal), and for their cytotoxicity in non-infected host cells (human foreskin fibroblasts, HFFs). The results revealed that the biological activity of the hybrids was influenced by both the nature of the carbohydrate (glucose or galactose) attached to the ruthenium complex and the type/length of the linker between the two units. For seven selected diruthenium-carbohydrate conjugates, the values of the half-maximal inhibitory concentration (IC50) on T. gondii β-gal and HFFs viability for a compound concentration of 2.5 μM were measured. Remarkably, two galactose-diruthenium conjugates, 23 and 26, performed significantly better than the corresponding unlabeled diruthenium complexes and the standard drug Pyrimethamine, with very low IC50 values (23: IC50 = 0.032 μM, 26: IC50 = 0.153 μM, Pyrimethamine, IC50 = 0.326 μM) and a very low toxicity on HFFs (viability 92% for 23 and 97% for 26). Overall, our study shows that conjugation of carbohydrates to diruthenium compounds is a promising approach to develop new effective antiparasitic compounds with reduced toxicity.

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