Lanthanide luminescent mesomorphic complexes with macrocycles derived from diaza-18-crown-6

Introducing Bulky Functional Lanthanide Cores into Thermotropic Metallomesogens: A Bottom‐Up Approach

“…Although two original strategies based on i) masking the Ln(NO 3 ) 3 core by using three wrapped aromatic strands in [Ln(L1) 3 X 3 ] [6,8,11] or ii) expulsing counterions in [Ln(L2-2H) 2 ] [9] successfully produced thermotropic mesophases, the design of polycatenar ligands possessing curved molecular interfaces appears as a complementary and versatile tool for forcing microsegregation processes to occur in these systems. [5,12,21,22] The bent interfaces obviously favor columnar and cubic organizations (Fig. 4), which are generally associated with high viscosity, a severe drawback when considering potential applications of the metal-centered properties in fast-reorienting, switchable LC displays (LCDs).…”

“…Although the free ligands are nonmesomorphic, the rigidification of the central core induced by the introduction of Ln(NO 3 ) 3 in the macrocyclic cavity favors microsegregation processes, and the expected Col h mesophases were detected in the 58-200°C range. [21] Such rigidification processes are well-documented, and large macrocyclic polyamines, substituted with alkoxybenzoyl groups, have been reported by Lehn et al to form columnar phases. The mesophase stability was found to decrease with increasing size of the crowns, which was attributed to the growing conformational flexibility of the molecule, and thus to the quite substantial deviation from a disk-like structure.…”

“…[17] Besides DH cores m , which can be independently tuned by judicious design of the molecular structure of the rigid aromatic core, DS chains m is the second parameter amenable to chemical tuning, via the connection of an increased number of flexible chains to the central rigid core. [20] The resulting so-called polycatenar ligands L10 (tetracatenar), [21] L11 (hexacatenar), [21] and L12 (hexacatenar) [22] systematically display a lower T m than their two-chain analogues L6 (DT m = 106°C) and L8 (DT m = 107°C), diagnostic for a significant increase of DS chains m (i.e., a measure of the efficiency of filling the space adequately in the crystal, Fig. 3a).…”

Liquid‐Crystalline Ternary Rare‐Earth Complexes

“…In the last decade, there has been considerable activity in the research field of lanthanide-containing liquid crystals (which are also called lanthanidomesogens). [2,[9][10][11] Different types of ligands were used to design new classes of lanthanidomesogens: Schiff bases, [12][13][14][15][16][17][18][19][20][21][22] β-enamino ketones, [23] alkanoates, [24,25] 4-alkoxybenzoates, [26][27][28] phthalocyanines, [29,[29][30][31][32][33] porphyrins, [34,35] imidazo [4,5-f] [1,10]phenanthrolines, [36] β-diketonates, [37] crown ethers, [38][39][40] 2,6-bis-(benzimidazol-2Ј-yl)pyridines, [11,41,42] and polyoxometalatesurfactant complexes. [43] Most examples of lanthanidomesogens are thermotropic liquid crystals, although some examples of lyotropic lanthanidomesogens have also been reported.…”

Lanthanide-containing luminescent molecular edifices

“…The macrocyclic receptors are in fact built from three different synthons: (i) the (2,2) core for Ln III complexation, (ii) two spacers connected to the amine functions which also play the role of antenna for sensitizing the Ln III luminescence and (iii) long mesogenic alkoxy chains with 10, 12 or 16 carbon atoms connected to the spacers. The underlying principle of the synthesis is to firstly resort to a multistep synthesis of the entire substituent, spacer and alkoxy chain, under the form of a bromide or carboxyl, before coupling it with (2,2) [47]. One of these macrocycles is shown in Scheme 3.…”