Coupling of a <i>C</i>₂-Chiral Ferrocene with Phenylalkynyl Groups: Novel Ferrocenophanes Carrying Multiple Chiral Ferrocenyl Units

Upon treatment with CuCl/TMEDA (1:1) at a high [CuCl]/[1] ratio, enantiopure C2-chiral tetrasubstituted ferrocene 1 carrying phenylalkynyl groups is transformed into a novel family of chiral ferrocenophanes 2 and 3 with their ferrocenyl joints connected by a π-conjugated rigid bridge. Compound 3, which is reminiscent of the Escher’s endless staircase, is a single conformer with a one-handed helical chirality

A Stable Single Piece of Unimolecularly π-Stacked Porphyrin Aggregate in a Thixotropic Low Molecular Weight Gel: A One-Dimensional Molecular Template for Polydiacetylene Wiring up to Several Tens of Micrometers in Length

An amide-type copper porphyrin gelator having alkyldiacetylene tethers gives very transparent gel in Decalin, and the gel shows unique thixotropic behavior. One-dimensional aggregates generated in the gel act as templates for unimolecularly segregated polydiacetylene wiring upon UV irradiation on the surface. The polymerization along the aggregation goes to at least several micrometers long

[60]Fullerene-Motivated Organogel Formation in a Porphyrin Derivative Bearing Programmed Hydrogen-Bonding Sites

A tetraphenylporphyrin (1b) bearing amide groups at the 3,5-positions of the meso-phenyl groups is assembled into a two-dimensional sheetlike structure and acts as an organogelator. When [60]fullerene was added, the sheetlike structure was dramatically changed into a one-dimensional fibrous structure, and both the gelation ability and the gel stability were improved. The stoichiometry between [60]fullerene and 1b was determined to be 1:2. Examination utilizing SEM and TEM observations, UV−vis and ATR IR spectral analyses, and XRD analysis revealed that an amide−amide hydrogen-bonding interaction creates a cavity, the size of which is complementary to that of [60]fullerene, and these cavities are connected by another amide−amide hydrogen-bonding interaction to provide a one-dimensional multicapsular structure. This is a novel example that the superstructure constructed in an organogel system is drastically changed by added [60]fullerene

A Coordination Gelator That Shows a Reversible Chromatic Change and Sol−Gel Phase-Transition Behavior upon Oxidative/Reductive Stimuli

A novel coordination gelator exhibits reversible chromatic and sol−gel phase-transition phenomena triggered by thermal and chemical stimuli

Porphyrin Gels Reinforced by Sol−Gel Reaction via the Organogel Phase

Porphyrins bearing four urea-linked dodecyl groups (3a) or four urea-linked triethoxysilylpropyl groups (3TEOS) at their peripheral positions were synthesized. 3a tends to assemble into a sheetlike two-dimensional structure due to the predominant hydrogen-bonding interaction among the urea groups and acts as a moderate gelator of organic solvents. On the other hand, its Cu(II) compelx (3a·Cu) tends to assemble into a fibrous one-dimensional structure due to the predominant porphyrin−porphyrin π−π stacking interaction and acts as an excellent gelator of many organic solvents. 3TEOS and 3TEOS·Cu, which also act as gelators, afforded similar superstructures as those of 3a and 3a·Cu, respectively, and as evidenced by SEM and TEM observations and XRD measurements, the original superstructures could be precisely immobilized by in situ sol−gel polycondensation of the triethoxysilyl groups. The TEM images of 3a gels and 3TEOS gels after sol−gel polycondensation showed a fine striped structure, the periodical distance of which was either 2 or 4 nm. X-ray crystallographic analysis of a single crystal obtained from a reference porphyrin bearing four urea-linked butyl groups revealed that there are two different porphyrin-stacked columns in the crystal and both the 2 nm distance and the 4 nm distance can appear, depending on the observation tilting angle. The hybrid gel prepared from 3TEOS·Cu by sol−gel polycondensation showed unique physicochemical properties such as a high sol−gel phase-transition temperature (>160 °C), sufficient elasticity, high mechanical strength, etc. Thus, the present study has established new concepts for molecular design of porphyrin-based gelators on the basis of cooperative and/or competitive actions of hydrogen-bonding and π−π stacking interactions and for immobilization of their superstructures leading to development of new functional organic/inorganic hybrid materials

Sol−Gel Reaction of Porphyrin-Based Superstructures in the Organogel Phase: Creation of Mechanically Reinforced Porphyrin Hybrids

We have demonstrated that a one-dimensional molecular assembly created by an H-aggregated porphyrin·Cu(II) stack can be immobilized, without a morphological change, by sol−gel polycondensation of the peripheral triethoxysilyl groups. The resultant gel prepared according to this flowchart has gained a very high thermal stability as well as a unique mechanical strength

Self-Sorting Organogels with p−n Heterojunction Points

Self-Sorting Organogels with p−n Heterojunction Point

Hydrogen-Bond-Assisted Control of H versus J Aggregation Mode of Porphyrins Stacks in an Organogel System

To obtain insights into a correlation relationship between the structure and the aggregation mode in an organogel system, we synthesized gelators 2a−4a bearing a porphyrin moiety as a one-dimensional aggregation unit and amide groups as peripheral hydrogen-bonding sites. Gelators 3a and 3b bearing the amide groups at the 4-position of the meso-phenyl groups are classified as versatile gelators, gelating 10 and 14 solvents, respectively, among 23 solvents tested herein. In contrast, gelators 2a and 4a bearing the amide groups at the 3,5-positions and 3-position, respectively, are classified as poor gelators. Examination by spectroscopic methods (UV−vis, ATR−FTIR, XRD, etc.) revealed that in the organogel phase porphyrins in 3a adopt the H aggregation mode whereas those in 2a and 4a adopt the J aggregation mode. X-ray analysis of the single crystals established that in fact 3b features a columnar stack of porphyrin moieties that can be classified as the H-aggregate, whereas 2a results in a two-dimensional a−b plane, in which porphyrin moieties are arranged in the J-aggregate. Very interestingly, the difference in the H versus J aggregation mode is well-reflected by the difference in the macroscopic aggregate morphology observed by SEM:  3a + cyclohexane gel results in a one-dimensionally aggregated fibrillar structure, whereas 2a + cyclohexane gel results in a two-dimensional sheetlike structure. These findings indicate that the H versus J aggregation mode of porphyrin stacks can be controlled by the peripheral hydrogen-bonding interactions and the microscopic hydrogen-bonding network structure is well-reflected by the macroscopic SEM-observed structure

Creation of a Mixed-Valence State from One-Dimensionally Aligned TTF Utilizing the Self-Assembling Nature of a Low Molecular-Weight Gel

One-dimensional TTF assemblies have been obtained through the design of low molecular-weight gels, which show a characteristic absorption band at around 1750 nm upon I2 doping, assignable to a mixed-valence state of the TTF assemblies

Polydiacetylene Nanofibers Created in Low-Molecular-Weight Gels by Post Modification: Control of Blue and Red Phases by the Odd−Even Effect in Alkyl Chains

The odd−even effect in alkyl chains of diacetylene gelators makes a strong effect in the effective conjugation length of the photopolymerized diacetylene in the gel phase