Cationic Polyelectrolyte for Anionic Cyanines: An Efficient Way To Translate Molecular Properties into Material Properties.

In this work, a new phosphonium-containing cationic polyelectrolyte () has been rationally designed and developed via a facile click-chemistry type postfunctionalization, which can form complexes with highly polarizable anionic cyanines to significantly reduce the strong and random cyanine-cyanine interactions (i.e., aggregation) in the solid-state.

Ultrafast energy transfer in biomimetic multistrand nanorings.

We report the synthesis of LH2-like supramolecular double- and triple-stranded complexes based upon porphyrin nanorings. Energy transfer from the antenna dimers to the π-conjugated nanoring occurs on a subpicosecond time scale, rivaling transfer rates in natural light-harvesting systems. The presence of a second nanoring acceptor doubles the transfer rate, providing strong evidence for multidirectional energy funneling.

Dioxaborine- and indole-terminated polymethines: effects of bridge substitution on absorption spectra and third-order polarizabilities.

Cyanine-like dyes are promising candidates for third-order nonlinear optical (NLO) applications such as all-optical switching. Here, we examine the consequences for linear and nonlinear optical properties of varying substituents on the central methine unit of bis(dioxaborine)-terminated anionic pentamethines and bis(indole)-terminated cationic heptamethines. The variation in absorption maxima and electrochemical potentials with structure can generally be rationalized using the Dewar-Knott rules, providing that mesomeric and inductive electron-withdrawal and donation are explicitly considered.

Using end groups to tune the linear and nonlinear optical properties of bis(dioxaborine)-terminated polymethine dyes.

Six anionic pentamethine dyes with different 2,2-difluoro-4-aryl-1,3,2(2 H)-dioxaborin-6-yl termini were synthesized and isolated as tetra-n-octylammonium salts with a variety of aryl groups appended to increase conjugation beyond the dioxaborine termini. The increased conjugation was expected to decrease the energy of the lowest-lying excited state, and increase the transition dipole moment linking this state to the ground state, which would be anticipated to result in an increase in the real part of the third-order polarizability, Re(gamma). UV/Vis-NIR absorption spectroscopy indicates that the absorption maxima in DMSO vary from 691 to 761 nm, with the longest wavelength transitions observed for a derivative where the aryl group is 4-nitrophenyl.

Synthesis and two-photon spectrum of a bis(porphyrin)-substituted squaraine.

A chromophore in which zinc porphyrin donors are linked through their meso positions by ethynyl bridges to a bis(indolinylidenemethyl) squaraine core has been synthesized using Sonogashira coupling. The chromophore exhibits a two-photon absorption spectrum characterized by a peak cross section of 11,000 GM and, more unusually, also exhibits a large cross section of >780 GM over a photon-wavelength window 750 nm in width.