Synthesis and Characterization of Unsymmetrically β-Substituted Porphyrin Liquid Crystals:  Influence of the Chemical Structure on the Mesophase Ordering

Abstract

The present study addresses the synthesis and characterization of a series of columnar liquid crystal compounds based on the natural porphyrin hemin. These compounds, which have different alkyl side chains (Alk = butyl, octyl, dodecyl, and hexadecyl) and either free base (M = 2H) or metalated (M = Zn, Cu) porphyrin cores, display hexagonal columnar mesophases over wide temperature ranges that cover room temperature. In the octyl, dodecyl, and hexadecyl free base compounds, the formation of a low-temperature mesophase (Colh1) on cooling from a high-temperature mesophase (Colh2) is marked by a slow transition. Furthermore, the X-ray diffraction pattern of the Colh1 mesophase indicates that intracolumnar noncovalent associations of three porphyrin molecules might be formed. As suggested by computer molecular modeling combined with the experimental data, the mobility of the propionic ester chains attached to the porphyrin core and the influence of metalation on porphyrin−porphyrin interactions may account for the mesophase structures encountered in the reported compounds.

Syntheses and Properties of meso‐Substituted Porphyrin Mesogens with Triazole Linkages and Peripheral Alkyl Chains

“…Porphyrins are used as cores in the syntheses of columnar liquid crystals (LCs). [14][15][16] Someo fthec olumnar phases can be homeotropically aligned in their pure state [10,12,13] or in the mixture with 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)C 61 (PCBM), [17] which holds great promise for high-performance electronic devices. Porphyrin occurs in nature (chlorophyll), and rothemund is the firstly synthesized porphyrin.…”

“…Unsymmetrical b-polysubstituted porphyrin ( Figure 2) synthesized from natural porphyrin hemin showing orderedh exagonal columnar phases (Col ho ), hexagonal columnar phases (Col h )a sw ell as discotic lamellar mesophase were reported too. [14][15][16] Someo fthec olumnar phases can be homeotropically aligned in their pure state [10,12,13] or in the mixture with 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)C 61 (PCBM), [17] which holds great promise for high-performance electronic devices. Ferroelectric coordination polymers are also realized by the co-assembly of lipophilic zinc porphyrin (ZnP) with ditopic bridging ligands.…”

“…[14][15][16] Scheme1.Synthetic route for porphyrin derivatives P/n-2 H, P/n-Zn and P/n-Cu.Reagents and conditions: (i)K 2 CO 3 ,p ropargyl bromide, acetone,508C, 12 h, 88 %; (ii)EtCO 2 H, pyrrole, 120 8C, 1h,23%;( iii)CuSO 4 ·5H 2 O, sodium ascorbate, tBuOHButanol/H 2 O = 1:1, THF,12h,6 5-78 %; (iv) Zn(Ac) 2 ·2H 2 O, CHCl 3 / MeOH = 3:1, reflux, 24 h, 80-85 %; (v) Cu(Ac) 2 ·H 2 O, CHCl 3 /MeOH = 3:1, reflux,24h,8 6-90 %. The thermal behavior,p hotophysical properties and morphologies of these compounds were investigated by polarizedo ptical microscopy (POM), differentials canning calorimetry (DSC),X RD, UV and PL, SEM and TEM.…”

Metallomesogens with Luminescent Behaviour: Palladium Complexes Derived from Alkylamide Tetraarylporphyrins

“…[20,21] The most significant LC behaviour was found by peripheral modification of octa-substituted and meso-tetraphenylporphyrinic derivatives. [2,[20][21][22][23][24][25][26][27][28] Additionally,s ome tetrapyrrolic macrocyclesp eripherally substituted have LCs properties and exhibit columnar mesophases. [29,30] Following our research interests in discotic LC and luminescent materials, [31][32][33] and considering the potential of functionalised meso-tetraarylporphyrins in this field, [34] we decided to prepareaseries of easily accessible porphyrins containing four (3a,b)o re ight (3c,d)a liphatic amide chains with different lengths.…”

An unsymmetrical porphyrin and its metal complexes: Synthesis, spectroscopy, thermal analysis and liquid crystal properties

“…[1][2][3][4][5] Porphyrin liquid crystals 6 are of interest for optoelectronic and other device applications due to their synthetic versatility, thermal stability, large electron systems and photochemical properties. These properties make them useful materials for charge transport, photoelectronic conversion, non-linear optics, organic light emitting diodes and optical information storage.…”