Viologen capped by nucleobase—building blocks for functional materials: synthesis and structure–properties relationship

Abstract

The current study presents a new class of functional derivatives (1–3) consisting of a dicationic viologen (4,4’-bipyridinium unit) (V2+) capped by nucleobases thymine (NB1), adenine (NB2), thymine/adenine (NB1, NB2), and ion-paired with amphiphilic anion 3,4,5-tris(dodecyloxy)benzene sulfonate (DOBS−). The target of our work focuses on the design and synthesis of molecular building blocks in which three different functionalities are combined: chromophore (V2+ unit), molecular recognition (NB unit), and thermotropic liquid crystal (DOBS unit). The resulted materials exhibit liquid crystalline properties at ambient temperature with significant particularities-induced by nucleobases in the mesogen structure. Structure–properties relationship study focuses on providing knowledge about (1) how the thermotropic, redox properties, thermochromism, or ionic conductive properties are influenced by the presence of purinic or pyrimidinic nucleobases, and (2) how effective is their ability to self-assembly by hydrogen bonding in nonpolar solvents. The presence of nucleobases has been proved to have a substantial impact on electron transfer rate during the reduction of viologen moieties by intermolecular aggregation. Ionic conductivity and thermochromic properties of derivatives 1–3 were investigated and compared to a non-containing nucleobase analog methyl viologen with 3,4,5-tris(dodecyloxy)benzene sulfonate anion (MV) as reference. Graphical abstract

Discotic Star Mesogen with Thymine Nucleobases Exhibiting a Rare Gyroid Cubic Mesophase with 3D Conductivity

“…[3][4] Thermotropic LCs with nucleobases are rare, but are known for uracil, adenine, thymine, cytosine or guanine bases attached to non-polar building blocks to generate rodshaped, wedge-shaped and phasmidic amphiphiles. [5][6][7][8][9][10][11][12][13] Discshaped mesogens with linked DNA bases have not been studied so far. Such mesogens can be envisaged by combination of star mesogen 2 and three thymine bases 3, which are tethered between the conjugated arms to give target molecule 1 (Scheme 1).…”

“…The liquid crystal (LC) colloidal state of matter of DNA was pivotal for the discovery of the DNA double helix and recognized for many DNA materials reported recently [3–4] . Thermotropic LCs with nucleobases are rare, but are known for uracil, adenine, thymine, cytosine or guanine bases attached to non‐polar building blocks to generate rod‐shaped, wedge‐shaped and phasmidic amphiphiles [5–13] . Disc‐shaped mesogens with linked DNA bases have not been studied so far.…”

“…Complementary DNA bases are the most obvious choice since they offer well known stable hydrogen bond arrays. Due to its thermal stability compared to other nucleobases, [9] we chose to implement thymine via a short oligomethylene spacer and discovered that this thymine‐filled discotic molecule generates a bicontinuous cubic phase (Cub v ) over a very broad temperature range down to room temperature.…”

Manufacturing of ultra-thin redox-active polymer films using the layer-by-layer method and co-polymerization of vinyl viologen units

“…The multilayer film could be also formed using LbL assembly techniques including: electrostatic interaction π-π * stacking [8][9][10], hydrogen bonding [11], coordination bonding [12], charge transfer [13], molecular recognition [14,15], adsorption/drying cycles [16], covalent bonds [17], etc. The deposition sequence of different materials defines the multilayer architecture and thus the device properties.…”