The Rainbow Arching over the Fluorescent Thienoviologen Mesophases
Giuseppina Anna Corrente,
Giuseppe Di Maio,
Massimo La Deda,
Odda Ruiz de Ballesteros,
Bartolo Gabriele,
Lucia Veltri,
Finizia Auriemma,
Amerigo Beneduci
Affiliations
Giuseppina Anna Corrente
Laboratory of Physical Chemistry, Materials and Processes for Industry, Environment and Cultural Heritage, Department of Chemistry and Chemical Technologies, University of Calabria, Via P. Bucci, Cubo 15D, 87036 Arcavacata di Rende, CS, Italy
Giuseppe Di Maio
Laboratory of Inorganic Molecular Materials, Department of Chemistry and Chemical Technologies, University of Calabria, Via P. Bucci, Cubo 14C, 87036 Arcavacata di Rende, CS, Italy
Massimo La Deda
Laboratory of Inorganic Molecular Materials, Department of Chemistry and Chemical Technologies, University of Calabria, Via P. Bucci, Cubo 14C, 87036 Arcavacata di Rende, CS, Italy
Odda Ruiz de Ballesteros
Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Monte Sant’Angelo, Via Cintia, 80126 Napoli, Italy
Bartolo Gabriele
Laboratory of Industrial and Synthetic Organic Chemistry (LISOC), Department of Chemistry and Chemical Technologies, University of Calabria, Via Pietro Bucci 12/C, 87036 Arcavacata di Rende, CS, Italy
Lucia Veltri
Laboratory of Industrial and Synthetic Organic Chemistry (LISOC), Department of Chemistry and Chemical Technologies, University of Calabria, Via Pietro Bucci 12/C, 87036 Arcavacata di Rende, CS, Italy
Finizia Auriemma
Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Monte Sant’Angelo, Via Cintia, 80126 Napoli, Italy
Amerigo Beneduci
Laboratory of Physical Chemistry, Materials and Processes for Industry, Environment and Cultural Heritage, Department of Chemistry and Chemical Technologies, University of Calabria, Via P. Bucci, Cubo 15D, 87036 Arcavacata di Rende, CS, Italy
Thermofluorochromic materials exhibit tunable fluorescence emission on heating or cooling. They are highly desirable for applications ranging from temperature sensing to high-security anti-counterfeiting. Luminescent matrices based on liquid crystals are very promising, particularly those based on liquid crystals with intrinsic fluorescence. However, only a few examples have been reported, suggesting ample margins for development in the field, due to the wide range of fluorophores and supramolecular organizations to be explored. Moreover, thermofluorochromic liquid crystals can be tailored with further functionalities to afford multi-stimuli responsive materials. For the first time, herein we report the thermofluorochromism of thienoviologen liquid crystals, already known to show bulk electrochromism and electrofluorochromism. In particular, we studied their photophysics in the 25 °C–220 °C range and as a function of the length of the N-linear alkyl chains, m (9 ≤ m ≤ 12 C atoms), and the type of anion, X (X = OTs-, OTf-, BF4-, NTf2-). Interestingly, by changing the parameters m, X and T, their fluorescence can be finely tuned in the whole visible spectral range up to the NIR, by switching among different mesophases. Importantly, by fixing the structural parameters m and X, an interesting thermofluorochromism can be achieved for each thienoviologen in a homologous series, leading to a switch of the emitted light from red to green and from white to blue as a consequence of the temperature-induced variation in the supramolecular interactions in the self-assembled phases.
