Femtosecond Molecular Photonics Materials

Nagamura, Toshihiko

doi:10.1007/978-3-642-58469-5_29

Cited by 4 publications

(2 citation statements)

References 30 publications

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“…Phthalocyanines (Pcs) and metallophthalocyanines (MPcs) have received considerable attention over the past 2 decades since their first synthesis in 1907 . Owing to their unique 18 π-electron delocalization system and intense metal−phthalocyanine interaction, these compounds exhibit large nonlinear susceptibilities and fast response, which lead to potential applications in photonic, − data processing, optical switching, optical limiting,and so on. Their structural stability and intense absorption in the near-IR region make phthalocyanines ideal candidates for photodynamic therapy (PDT). − However, their large π-conjugation also leads to a strong stacking tendency in solution, which usually decreases their luminescence quantum yields, shortens their triplet state lifetime, and reduces their photosensitizing efficiencies.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Excited State Dynamics of Modified Phthalocyanines: p-HPcZn and p-HPcCo

Yan

et al. 2006

J. Phys. Chem. A

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Two modified metallophthalocyanines (MPcs) containing sulfonic naphthoxy substituents were synthesized. The measurements of transient absorption and time-resolved photoluminescence were used to study the ultrafast response and excited state dynamics of two MPcs in dimethyl sulfoxide (DMSO) solution, which were predominantly in the monomeric form. Under excitation at 400 nm, these molecules experience vibrational relaxation to the bottom of the first excited state and then the excitation rapidly converts to the low-lying charge-transfer (CT) state and finally reaches the triplet states. Under excitation at 800 nm, they show a two-photon absorption character, and their excited state dynamics exhibit strong dependence on the probe wavelength. The main results with 400 nm pumping are similar to the results with 800 nm pumping. For p-HPcZn, weak two-photon photoluminescence was also observed with a lifetime of 52 +/- 2 ps. A four-level model was used to illustrate the excited state dynamics of p-HPcZn, while a five-level model was suggested for p-HPcCo molecule.

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Section: Introductionmentioning

confidence: 99%

Ultrafast Excited State Dynamics of Modified Phthalocyanines: p-HPcZn and p-HPcCo

Yan

et al. 2006

J. Phys. Chem. A

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“…Phthalocyanines (Pcs) have been studied extensively because of their applications in photonics, − data storage, photocatalysis, − photodynamic therapy, , and solar energy conversion. , Optical properties of Pcs can be controlled and manipulated through binding different metal ions with various axial ligands, and covalently attaching different side groups. − In particular, Pcs self-assemble into nanometer scaled aggregates via nonbonding interactions, such as π-stacking, in films, liquid crystals, and solutions, and such stacking can be controlled via chemical modifications. − One of the approaches of controlling self-assembly is through steric hindrance of peripheral groups which prevent the π-stacking. Hence, the self-assembly of Pcs can be regulated by these two structural factors exerting two opposite effects.…”

Section: Introductionmentioning

confidence: 99%

Excited State Dynamics and Structures of Functionalized Phthalocyanines. 1. Self-Regulated Assembly of Zinc Helicenocyanine

et al. 2005

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Recently synthesized zinc helicenocyanine (ZnHc), where four helicene groups are fused with a phthalocyanine (Pc) core through all-carbon linkages, exhibits an unusually strong tendency of forming soluble molecular aggregates in organic solvents. The aggregation results in a strong optical absorption across most of the visible region, which is drastically different from that of its monomer. The aggregation is suppressed by dissolving ZnHc in a liquid crystal, octylbiphenylcarbonitrile (OBCN), where the monomer ZnHc dominates and exhibits a typical optical absorption spectrum of monomeric zinc phthalocyanine, except red shift in both Q- and B- bands due to pi-conjugation expansion. This study correlates optical properties and excited state dynamics of ZnHc with intra- and intermolecular electronic interactions, using quantum mechanical calculations and ultrafast transient absorption spectroscopy. Structural details of the aggregates are revealed by small-angle X-ray scattering (SAXS) to be uniformly dimers with alkoxy chains wrapped around the core of a face-to-face dimer. The results suggest that while the peripheral helicene moieties in ZnHc are electronically coupled to the Pc core via expansion of the pi-conjugation of the macrocycle, the coupling is attenuated by the "lock washer" conformation of the nonplanar peripheral helicenes which prevents pi-conjugation throughout the entire macrocycle. The interplay between pi-conjugation expansion in the macrocyle plane and the pi-pi stacking out of the macrocyle plane produces a structure that facilitates the unique optical properties and self-regulated assembly into nanoscale structures in solution. These novel optical properties are explored for potential applications in various areas.

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Nonlinear Optical Properties of Porphyrins

et al. 2007

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Porphyrins and phthalocyanines have outstanding chemical and thermal stability. The macrocyclic structure and chemical reactivity of tetrapyrroles offers architectural flexibility and facilitates the tailoring of chemical, physical and optoelectronic parameters. The specific optical properties of the tetrapyrrole macrocycle combined with the synthetic methodologies now available and the already available theoretical and spectroscopic knowledge on their optical behavior make porphyrins a target of choice for this area. They are versatile organic nanomaterials with a rich photochemistry and their excited state properties are easily modulated through conformational design, molecular symmetry, metal complexation, orientation and strength of the molecular dipole moment, size and degree of conjugation of the π‐systems, and appropriate donor‐acceptor substituents. Here we review the structural chemistry and optical properties of recently synthesized porphyrin derivatives that offer potential for nonlinear optical (NLO) applications and complement existing studies on phthalocyanines. Classes of interest include the classic A4 symmetric tetrapyrroles, while optimized systems include push‐pull porphyrins, oligomeric and supramolecular self‐assembled systems, films and nanoparticle systems, and highly conjugated porphyrin arrays.

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Femtosecond Molecular Photonics Materials

Cited by 4 publications

References 30 publications

Ultrafast Excited State Dynamics of Modified Phthalocyanines: p-HPcZn and p-HPcCo

Ultrafast Excited State Dynamics of Modified Phthalocyanines: p-HPcZn and p-HPcCo

Excited State Dynamics and Structures of Functionalized Phthalocyanines. 1. Self-Regulated Assembly of Zinc Helicenocyanine

Nonlinear Optical Properties of Porphyrins

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