https://hdl.handle.net/10481/49255 Sat, 18 Apr 2026 02:54:21 GMT 2026-04-18T02:54:21Z https://hdl.handle.net/10481/99107 Versatile synthesis and enlargement of functionalized distorted heptagon-containing nanographenes Rodríguez Márquez, Irene; Fuentes Romero, Noelia; Moreno Cruz, Carlos; Puente Muñoz, Virginia; Sotorrios, Lia; Marcos, Maria Luisa; Choquesillo Lazarte, Duane; Biel Ruiz, Blanca; Crovetto González, Luis; Gómez Bengoa, Enrique; González Pérez, María Teresa; Martín, Rubén; Cuerva Carvajal, Juan Manuel; González Campaña, Araceli Highly distorted polycyclic aromatic hydrocarbons (PAHs) are predicted to be attractive goals in nanoscience owing to the new properties they can exhibit. We have shown that a variety of functionalized distorted heptagon-containing nanographenes can be easily prepared from simple building blocks by a sequence of Co-catalyzed cyclotrimerization and cyclodehydrogenation reactions. The versatility of this strategy allows easy subsequent enlargement of these nanostructures by Ni-catalyzed cross-coupling and final cyclodehydrogenation reactions. Soluble extended distorted nanographenes 1 and 2 containing heptagon and an edge-shared pentagon–heptagon combination have been synthesized. High distortion of the polycyclic backbone of 2 caused by non-hexagonal rings and a helicene moiety was confirmed by X-ray crystallography. Experimental data reveal promising optical and electronic properties for distorted PAHs with long fluorescence lifetimes (up to 14.5 ns) and low band gaps (down to 2.27 eV). This straightforward and versatile synthetic strategy, the observed long fluorescence lifetimes and the small optical and electrochemical band gaps for the presented compounds may promote the future implementation of distorted graphene molecules in electronic devices. https://hdl.handle.net/10481/99107 https://hdl.handle.net/10481/98067 Efficient Transfer of Chirality in Complex Hybrid Materials and Impact on Chirality-induced Spin Selectivity Illescas Lopez, Sara; Mañas Torres, Mari C.; Contreras-Montoya, Rafael; Firouzeh, Seyedamin; Gavira, Jose A.; Álvarez de Cienfuegos Rodríguez, Luis; Pramanik, Sandipan; Rahman, Md. Wazedur; Hossain, Md. Anik Transfer of chirality, or transmission of asymmetric information from one system to another, plays an essential role in fundamental biological and chemical processes and, therefore, is essential for life. This phenomenon also holds immense potential in spintronics in the context of chirality-induced spin selectivity (CISS). In the CISS, the spatial arrangement of chiral molecules influences the spin state of electrons during the charge-transfer processes. Transfer of chirality from chiral molecules to an achiral material in a hybrid environment enables induction of spin polarization in the achiral material, thus vastly expanding the library of CISS-active electronic materials. Such “induced” CISS signals could have different responses compared to pure chiral molecules because the electronic properties of the achiral material come into play in the former case. In addition, multiple chiral sources can be used, which can have a nontrivial contribution to the induced CISS effect and can act either synergistically or antagonistically. This opens the way to achieving tunability of the CISS signals via chemical means. Earlier, such a chirality-transfer phenomenon and the resulting induced CISS effect were demonstrated in a hybrid system containing carbon nanotubes (CNTs) functionalized with a chiral agent (Fmoc-diphenylalanine l/d). In this context, we extend this result by investigating the role of an additional chiral moiety (l-lysozyme enzyme crystals) in this system. Here, the chiral crystal surrounds the chiral-functionalized CNTs, and we show that synergistic interactions result in more efficient chirality transfer, resulting in nontrivial changes in the CISS effect. This manifests in the form of (a) a stronger CISS signal compared to only one single chiral agent, (b) nonmonotonic temperature dependence and sign reversal of the CISS signal, and (c) persistence of the CISS signal at higher temperatures. Hybrid chiral materials with multiple chiral sources could, therefore, offer intricate control of the CISS signal via modification of its constituents, which is not possible in homogeneous chiral systems with single chiral sources. https://hdl.handle.net/10481/98067 https://hdl.handle.net/10481/84311 Chirality-Induced Spin Selectivity in Supramolecular Chirally Functionalized Graphene Firouzeh, Seyedamin; Illescas Lopez, Sara; Hossain, Md. Anik; Cuerva Carvajal, Juan Manuel; Álvarez de Cienfuegos Rodríguez, Luis; Pramanik, Sandipan Chiral graphene hybrid materials have attracted significant attention in recent years due to their various applications in the areas of chiral catalysis, chiral separation and recognition, enantioselective sensing, etc. On the other hand, chiral materials are also known to exhibit chirality-dependent spin transmission, commonly dubbed “chirality induced spin selectivity” or CISS. However, CISS properties of chiral graphene materials are largely unexplored. As such, it is not clear whether graphene is even a promising material for the CISS effect given its weak spin−orbit interaction. Here, we report the CISS effect in chiral graphene sheets, in which a graphene derivative (reduced graphene oxide or rGO) is noncovalently functionalized with chiral Fmoc-FF (Fmocdiphenylalanine) supramolecular fibers. The graphene flakes acquire a “conformational chirality” postfunctionalization, which, combined with other factors, is presumably responsible for the CISS signal. The CISS signal correlates with the supramolecular chirality of the medium, which depends on the thickness of graphene used. Quite interestingly, the noncovalent supramolecular chiral functionalization of conductive materials offers a simple and straightforward methodology to induce chirality and CISS properties in a multitude of easily accessible advanced conductive materials. https://hdl.handle.net/10481/84311 https://hdl.handle.net/10481/83916 Chirality-induced Spin Selectivity in Functionalized Carbon Nanotube Networks: The Role of Spin-orbit Coupling Firouzeh, Seyedamin; Illescas Lopez, Sara; Hossain, Md. Anik; Cuerva Carvajal, Juan Manuel; Álvarez Cienfuegos Rodríguez, Luis; Pramanik, Sandipan Spin–orbit coupling in a chiral medium is generally assumed to be a necessary ingredient for the observation of the chirality-induced spin selectivity (CISS) effect. However, some recent studies have suggested that CISS may manifest even when the chiral medium has zero spin–orbit coupling. In such systems, CISS may arise due to an orbital polarization effect, which generates an electromagnetochiral anisotropy in two-terminal conductance. Here, we examine these concepts using a chirally functionalized carbon nanotube network as the chiral medium. A transverse measurement geometry is used, which nullifies any electromagnetochiral contribution but still exhibits the tell-tale signs of the CISS effect. This suggests that CISS may not be explained solely by electromagnetochiral effects. The role of nanotube spin–orbit coupling on the observed pure CISS signal is studied by systematically varying nanotube diameter. We find that the magnitude of the CISS signal scales proportionately with the spin–orbit coupling strength of the nanotubes. We also find that nanotube diameter dictates the supramolecular chirality of the medium, which in turn determines the sign of the CISS signal. https://hdl.handle.net/10481/83916 https://hdl.handle.net/10481/79903 Transverse Magnetoconductance in Two-Terminal Chiral Spin-Selective Devices Hossain, Md. Anik; Illescas Lopez, Sara; Nair, Rahul; Cuerva Carvajal, Juan Manuel; Álvarez Cienfuegos Rodríguez, Luis; Pramanik, Sandipan The phenomenon of chirality induced spin selectivity (CISS) has triggered significant activity in recent years, although many aspects of it remain to be understood. For example, most investigations are focused on spin polarizations collinear to the charge current, and hence longitudinal magnetoconductance (MC) is commonly studied in two-terminal transport experiments. Very little is known about the transverse spin components and transverse MC – their existence, as well as any dependence of this component on chirality. Further, measurement of the CISS effect via two-terminal MC experiments remains a controversial topic. Detection of this effect in the linear response regime is debated, with contradicting reports in the literature. Finally, potential influence of the well-known electric magnetochiral effect on CISS remains unclear. To shed light on these issues, in this work we have investigated the bias dependence of the CISS effect using planar carbon nanotube networks functionalized with chiral molecules. We find that (a) transverse MC exists and exhibits tell-tale signs of the CISS effect, (b) transverse CISS MC vanishes in the linear response regime establishing the validity of Onsager’s relation in two-terminal CISS systems, and finally (c) CISS signal remains present even in the absence of electric magneto chiral effects, suggesting existence of an alternative physical origin of CISS MC. https://hdl.handle.net/10481/79903