Recognition processes occuring at the molecular level may lead to changes at the level of the material, thus expressing molecular information on the macroscopic scale. This is the case namely when the formation of a complementary supramolecular pair E 3 induces the appearance of a liquid crystalline phase. ''] If two (or more) units E or 3 are grafted onto a template T, mixing TE, with the complementary T3,,, may lead to the self-assembly of a linear or cross-linked polymeric supramolecular species (TE, ,T3,,,)" whose existence is conditioned by the molecular recognition directed association between the E and 3 groups.[21 Figure I represents schematically such * + + mEZ,T32).Fig. 1, Schematic representation of the formation of a polymeric supramolecular species (TE,, T3,)" by association of two complementary ditopic components TE, and T3,. [**I We thank Dr. Frunpise Livulunt for discussion of the optical textures. a process in the case of two-site (ditopic) complementary components TE, and T3,. The resulting supramolecular polymeric material (TE,, T32)n may present liquid crystalline properties if suitable chains are introduced onto the components. We now describe results obtained along these lines in the case where T is a group derived from tartaric acid and the complementary units E, 3 are of uracil (U) and 2,6-diacylamino-pyridine (P) type. The formation of triply hydrogenbonded complementary pairs by these units is well documentedF3 -and has been used in separation procedures[41 in macrocyclic receptor molecules ['I and for inducing the appearance of supramolecular mesophases."] The tartaric acid (T) unit provides in addition the opportunity to investigate the effect of changes in chirality on the properties of the species formed. The required components LP,, LU,, DP,, MP, and MU, derived from L( +), D( -) and meso (M) tartaric acid respectively, have been synthesized in a straightforward fashion. Alkylation of the L( + )-N,N,NN-tetramethyltartramide L-lL6] by treatment with NaH in DMF followed by C,,H,,OTS[~~ gave the bis-ether L-2 (80%; mp < 50°C; from hexane; [a]:' = + 45", c = 0.1, CHCl,), which was hydrolyzed with aqueous HCI (25 %) at reflux[*] to the diacid L-3 (65 YO; mp 76 "C; from hexane; [a];5 = + 14.7", c = 0.9, CHC1,). Treatment of L-3 with PCI, in CH,C1, (18 h, rt)['] gave the corresponding bis-acid chloride which by reaction with 6-hydroxymethyl uracil['] (in HMPA) and with 2,6-diacetylamino-4-(hydroxyethyl)oxy-pyridine~101 (in DMF) in the presence of 4-dimethylaminopyridine (2 eq.; 2 h; rt) afforded respectively the desired compounds LU, (50 %, [a];5 = + 37", c = 0.5, THF) and LP, (27%; [a];' = + 25.5", c = 0.5, THF) after purification by chromatography and crystallization from THF and aqueous ethanol respectively. Following the same reaction sequence D( -) tartaric acid gave DP, (23 %; [a];' = -25.4", c = 0.5, THF). RCOCH(OR)CH(OR)COR' 1 2 3 R = H, R = N(CH,), R = C,,H,,, R' = N(CH3), R = C,,H,,, R' = OH The corresponding compounds derived from meso-tartaric acid were obtained in a similar ...

The DNA molecule is extremely compacted in bacteria, in cell nuclei, sperm heads and virus capsids. These interactions between DNA molecules are important to our understanding of chromatin condensation. DNA forms multiple liquid-crystalline phases whose nature depends on the polymer concentration, and it has been suggested that the highly concentrated phase of 50-nm DNA molecules is two-dimensionally ordered and smectic-like. We rule out this smectic hypothesis and demonstrate by polarizing microscopy, electron microscopy and X-ray diffraction that this phase is characterized by a columnar longitudinal order and a hexagonal lateral order, with intermolecular distances ranging from 2.8 to 4.0 nm depending on the DNA concentration.