A shape-persistent arylene ethynylene macrocycle with a multiple acetamide modified cavity: synthesis and gelation.

A new arylene ethynylene macrocycle (AEM) molecule bearing endo-acetamide groups was obtained by a Pd/Cu mediated homo-coupling reaction. Introducing tetraethylene glycol ether as a linkage between two C-shaped fragments substantially improved the final cyclization yield (30%). Concentration-dependent 1HNMR experiments indicated that strong aggregates formed through H-bonds were observed for this new macrocycle with amide groups in solution. And also, this macrocycle was fluorescent in solution and showed a highly selective fluorescence quenching response toward the highly toxic Hg2+. More importantly, this macrocycle could induce gelation of several solvents. Significantly, an interesting aggregation-induced enhanced emission (AIEE) behavior was observed for this macrocycle upon gelation. Both SEM and TEM investigations revealed that nanoporous structures existed in the xerogels. This study offers a new molecular design approach to develop fluorescent gels from planar AEM molecules with a functional cavity.

Donor-Acceptor Conjugated Macrocycles: Synthesis and Host-Guest Coassembly with Fullerene toward Photovoltaic Application.

Electron-rich (donor) and electron-deficient (acceptor) units to construct donor-acceptor (D-A) conjugated macrocycles were investigated to elucidate their interactions with electron-deficient fullerene. Triphenylamine and 4,7-bisthienyl-2,1,3-benzothiadiazole were alternately linked through acetylene, as the donor and acceptor units, respectively, for pentagonal 3B2A and hexagonal 4B2A macrocycles. As detected by scanning tunneling microscopy, both D-A macrocycles were found to form an interesting concentration-controlled nanoporous monolayer on highly oriented pyrolytic graphite, which could effectively capture fullerene. Significantly, the fullerene filling was cavity-size-dependent with only one C70 or PC71BM molecule accommodated by 3B2A, while two were accommodated by 4B2A. Density functional theory calculations were also utilized to gain insight into the host-guest systems and indicted that the S···π contact is responsible for stabilizing these host-guest systems. Owing to the ellipsoidal shape of C70, C70 molecules are standing or lying in molecular cavities depending on the energy optimization. For the 3B2A/PC71BM blended film, PC71BM was intercalated into the cavity formed by the macrocycle 3B2A and provided excellent power conversion efficiency despite the broad band gap (2.1 eV) of 3B2A. This study of D-A macrocycles incorporating fullerene provides insights into the interaction mechanism and electronic structure in the host-guest complexes. More importantly, this is a representative example using D-A macrocycles as a donor to match with the spherical fullerene acceptor for photovoltaic applications, which offer a good approach to achieve molecular scale p-n junctions for substantially enhanced efficiencies of organic solar cells through replacing linear polymer donors by cyclic conjugated oligomers.

A template-confined fabrication of controllable gold nanoparticles based on the two-dimensional nanostructure of macrocycles.

An amine-substituted macrocycle , a rigid hexagonal ring, self-assembled into network architecture on the surface, which could be used as a molecular template to directly fabricate gold nanoparticles (AuNPs) with narrow size distribution (2.2 ± 0.1 nm). This work demonstrated a new pathway for the formation of controllable AuNPs on the surface.

Two-dimensional supramolecular spring: coordination driven reversible extension and contraction of bridged half rings.

A tetraethylene glycol ether bridged derivative 9 has been designed and synthesized, and its two-dimensional (2D) self-assembled behavior has been investigated at the single-molecule level. Our results revealed that 9 generally adopted the fully extended state but changed to the contracted state when triggered by K2CO3, and recovered the original fully extended conformation after subsequent addition of 18-crown-6. Such a coordination-controlled reversible assembly reveals supramolecular springs in response to chemical stimuli, which is of great interest in bionics and materials science.

1-[(3-Chloro-phen-yl)(morpholin-4-yl)-meth-yl]naphthalen-2-ol.

In the title compound, C(21)H(20)ClNO(2), the dihedral angle between the naphthyl-ene ring system and the phenyl ring is 77.86 (15)°. The morpholine ring adopts a chair conformation. The hydroxyl group is involved in intra-molecular O-H⋯N hydrogen bonding. A weak inter-molecular C-H⋯π inter-action is present in the crystal structure.

Two-dimensional self-assembly of linear molecular rods at the liquid/solid interface.

We report on the synthesis and scanning tunneling microscopy (STM) studies of a series of linear molecular rods (1-5) comprising different numbers and/or spatial arrangements of perfluorinated benzene and benzene subunits interlinked with diacetylenes in the para position and decorated with or without terminal dodecyl chains. The molecules organize themselves into well-ordered 2D crystal structures at the liquid/solid interface through intermolecular and molecule-substrate interactions. Whereas the molecules substituted by dodecyl chains form the lamellar structures with alternating rigid core rows and alkyl chain rows, the unsubstituted ones change the orientation of the rigid backbones with respect to the lamellar axis. The molecular arrangement is not influenced by fluoro substituents on any phenyl ring of the backbone, which suggests that the interactions between the π-conjugated backbones are dominated by close packing rather than by the dipole moments of the rods or fluorine-based intermolecular interactions.

Shape-persistent macrocycles comprising perfluorinated benzene subunits: synthesis, aggregation behaviour and unexpected mu-rod formation.

The synthesis of a series of shape-persistent macrocycles (SPMs) (1-4 and 6) comprising different numbers and/or spatial arrangement of meta-substituted tetrafluorobenzene and benzene subunits interlinked with diacetylenes is described. To increase their solubility, all five SPMs were functionalized by four peripheral hexyl chains. These SPMs were assembled from common diacetylene building blocks by a modular synthetic strategy based on palladium and/or copper catalyzed versions of acetylene coupling reactions (oxidative acetylene coupling and Cadiot-Chodkiewicz coupling). The aggregation properties in chloroform of SPMs 1-6 were investigated by concentration- and temperature-dependent 1H-NMR investigations and by vapour pressure osmometry studies. Aggregation constants and thermodynamic data of the process were obtained by least-squares fitting of the NMR data and by van't Hoff analysis respectively. Aggregation was only observed for SPMs 2-6 comprising electron deficient tetrafluorobenzene corner units. While dimerization was the major aggregation process for SPMs 3-6, the formation of larger aggregates in solution was only observed for SPM 2. The formation of aggregates is in all cases enthalpically driven. As the largest and the smallest enthalpic contribution and entropic loss in the series of aggregating SPMs were found for the two SPMs 3 and 4, each comprising two fluorinated corner units, the spatial arrangement of these subunits within the macrocycle seems to be at least equally important as the ratio of tetrafluorobenzene and benzene moieties. Interestingly, micro-scaled hexagonal rods were formed from SPM 3 upon heating in toluene, presumably consisting of mixtures of oligomers arising from covalently interlinked macrocycles.

Two dimensional chiral networks emerging from the aryl-F...H hydrogen-bond-driven self-assembly of partially fluorinated rigid molecular structures.

Self-assembly of the partially fluorinated rigid molecules physisorbed at solution/graphite interface has been investigated by scanning tunneling microscopy. Upon adsorption, both the branched star-shaped compound 1 and the angulate rod 2 compromising diacetylene and acetylene interlinked benzene and pentafluorobezene formed two-dimensional chiral porous networks. The spontaneous formation of these architectures is likely attributed to the two effects: the compensation of the dipole moments of the branches and the formation of Ar-H...F hydrogen bonds. These results demonstrate that the immobilization of molecules at the liquid/solid interface can be driven by these weak intermolecular interactions instead of van der Waals interactions between alkyl chains and substrate.

Shape-persistent macrocycle with a self-complementary recognition pattern based on diacetylene-linked alternating hexylbenzene and perfluorobenzene rings.

The synthesis and characterization of a shape-persistent macrocycle, consisting of alternating electron rich and electron poor sub-units as a self-complementary recognition pattern, is reported, and its increased tendency to form dimer complexes in solution is demonstrated and discussed.

A self assembled molecular zipper based on a perfluorophenyl-phenyl diacetylene motif.

The synthesis and characterization of a molecular rod consisting of a pentafluorophenyl and a para-dodecylphenyl subunit linked by a diacetylene and its large area self assembly into perfect parallel lines consisting of interlocked molecular rods are reported and discussed.

Double-helical ultrastructure of polycationic dendronized polymers determined by single-particle Cryo-TEM.

The ultrastructure of cationic dendronized polymers (denpols) of third and fourth generations (PG3 and PG4) in water was determined by using single-particle cryo-transmission electron microscopy (cryo-TEM). At concentrations in the region of 50 mg L(-1), networks of double-stranded fibers were revealed that exhibit well-defined diameters of 5.9 nm+/-0.4 nm for PG3 and 7.4 nm+/-0.4 nm for PG4. The structure varies with progression along the fibers, and includes a double helix with a pitch of 7.0+/-0.4 nm for PG3 and 9.0+/-0.4 nm for PG4. The formation of the double strands is attributed to the hydrophobic effect and limited crowding in the dendron shell of the third and fourth generation denpols investigated. From solutions of lower concentrations (around 10 mg L(-1)), isolated molecular fibers were adsorbed onto high-energy surfaces and examined by performing scanning force microscopy (SFM) on mica, and after staining, TEM on glow-discharged carbon films. In both cases, characteristic undulations of single strands were observed, which are attributed largely to the adsorption process.

Molecular structure of single DNA complexes with positively charged dendronized polymers.

Positively charged dendronized polymers with protonated amine groups at the periphery and different dendron generations are cylindrically shaped nanoobjects whose radii and linear charge densities can be varied systematically. These polyelectrolytes have been complexed with DNA and subsequently adsorbed on precoated mica substrates. The analysis of scanning force microscopy data indicates that DNA wraps around the dendronized polymers. The calculated pitch is 2.30 +/- 0.27 and 2.16 +/- 0.27 nm for DNA wrapped around dendronized polymers of generation two and four, respectively. The complex with the second generation has been shown to be negatively charged, which is consistent with the theory of spontaneous overcharging of macro-ion complexes, when the electrostatic contribution to the free energy dominates over the elastic energy. The complexes may be of interest for the development of nonviral gene delivery systems.