α-Bridged BODIPY oligomers with switchable near-IR photoproperties by external-stimuli-induced foldamer formation and disruption.

We designed and synthesized a series of new α-bridged linear BODIPY oligomers, which exhibited strong absorption and high fluorescence efficiency in the near infrared region. The oligomers can be reversibly converted to the first NIR emissive BODIPY foldamers upon selective complexation with Cs(+).

Structural interconversion and regulation of optical properties of stable hypercoordinate dipyrrin-silicon complexes.

Novel pentacoordinate dipyrrin-silicon complexes showed efficient red or near-IR fluorescence, and the structural interconversion between silanol and siloxane derivatives resulted in significant changes in the optical properties.

Cation recognition and pseudorotaxane formation of tris-dipyrrin BF2 macrocycles.

Macrocyclic planar tris-dipyrrin BF(2) complexes exhibit strong alkali-metal recognition and pseudorotaxane formation ability with a secondary ammonium salt through BF(2)-cation interactions.

Aluminium complexes of N2O2-type dipyrrins: the first hetero-multinuclear complexes of metallo-dipyrrins with high fluorescence quantum yields.

The aluminium complexes of N(2)O(2)-dipyrrins were synthesized and the absorption/fluorescence spectral changes caused by the complex formation with ZnCl(2), ZnBr(2) and Zn(OAc)(2) were examined.

Synthesis and guest recognition ability of 2,3-dimethoxy-1,4-phenylene-containing porphyrinoids.

The acid-catalyzed condensation of the bispyrrolylbenzene derivative and benzaldehyde yielded macrocycles 1 and 2 bearing three and four dipyrrin units which are connected by 2,3-dimethoxy-1,4-phenylene rings. The cationic guest recognition ability of 1 was investigated by UV-vis absorption, (1)H NMR spectroscopic techniques, and ab initio calculations (HF/3-21G(*)). The tris-dipyrrin macrocycle 1 was found to recognize alkali metals in the O6 binding cavity.

Self-assembled cyclic boron-dipyrrin oligomers.

Self-assembled cyclic boron-dipyrrin oligomers 3-5 obtained by the reaction of catecholyldipyrrin with boron trichloride were characterized by 1H NMR, MALDI-TOF MS, and X-ray measurements and the interaction between 3 and alkali metal ions was examined.

Dimeric assemblies from 1,2,3-triazole-appended Zn(II) porphyrins with control of NH-tautomerism in 1,2,3-triazole.

Cu(I)-catalyzed 1,3-dipolar cycloaddition of meso-ethynyl Zn(II) porphyrin with benzyl azide efficiently provides meso-1-benzyl-1H-1,2,3-triazolyl Zn(II) porphyrin, which assembles to form a slipped cofacial dimer by the complementary coordination of the triazole nitrogen atom at the 3-position to the zinc center of a second porphyrin moiety both in the solid and solution states. Removal of the benzyl protection and introduction of a 2-ethoxycarbonylphenyl moiety greatly stabilize the dimeric assembly through an additional hydrogen bonding interaction between the NH proton of 2H-1,2,3-triazole and the carbonyl oxygen.

Relationship between two-photon absorption and the pi-conjugation pathway in porphyrin arrays through dihedral angle control.

Recently, covalently linked or self-assembled porphyrin array systems have attracted much attention for their enhanced two-photon absorption (TPA) behaviors. In this study, we have investigated the TPA properties of various dihedral angle controlled, directly linked porphyrin dimers and arrays to elucidate the relationship between the pi-conjugation pathway and TPA properties. We have demonstrated a strong correlation between pi-conjugation (aromaticity) and TPA properties in porphyrin assemblies.

Excitation-energy migration in self-assembled cyclic zinc(II)-porphyrin arrays: a close mimicry of a natural light-harvesting system.

The excitation-energy-hopping (EEH) times within two-dimensional cyclic zinc(II)-porphyrin arrays 5 and 6, which were prepared by intermolecular coordination and ring-closing metathesis reaction of olefins, were deduced by modeling the EEH process based on the anisotropy depolarization as well as the exciton-exciton annihilation dynamics. Assuming the number of energy-hopping sites N = 5 and 6, the two different experimental observables, that is, anisotropy depolarization and exciton-excition annihilation times, consistently give the EEH times of 8.0 +/- 0.5 and 5.3 +/- 0.6 ps through the 1,3-phenylene linkages of 5 and 6, respectively. Accordingly, the self-assembled cyclic porphyrin arrays have proven to be well-defined two-dimensional models for natural light-harvesting complexes.

Helicity induction and two-photon absorbance enhancement in zinc(II) meso-meso linked porphyrin oligomers via intermolecular hydrogen bonding interactions.

Helicity has been induced in meso-meso linked oligomers by hydrogen bonding host-guest interactions with cyclic urea. Helical porphyrin arrays thus formed exhibit chirality amplification and enhanced two-photon absorption properties.

Proofs of macrocyclization of gable porphyrins as mimics of photosynthetic light-harvesting complexes.

Porphyrin macrocycles composed of five and six units of m-gable imidazolylporphyrinatozinc (1-Zn) were synthesized by self-assembled cyclization followed by ring-closing metathesis linkings. Each porphyrin macrocycle was isolated by GPC chromatography, and their molecular weights were determined by MALDI-TOF mass spectroscopy. These structures represent mimics of light-harvesting complexes in photosynthetic bacteria. [structure: see text]

Long rod-like array of bis(imidazolyl)porphyrinatocobalt(III) by successive complementary coordination.

Simple bis(imidazolyl)porphyrin cobalt(III) complex was found to form a long polymeric array by complementary coordination of imidazole to cobalt ion. Formation of higher ordered assemblies was also observed.