A Multi‐Addressable Photochromic 1,2‐Dithienylcyclopentene‐Phenoxynaphthacenequinone Hybrid

Abstract

[16] a) Assuming a hexagonal arrangement of the porous structures of the micro-and meso-porous silica matrices, FSM-16, as indicated in the XRD and TEM results, Equation 1 can be derived from a geometrical consideration,where W 0 is the pore volume per unit weight, a is the lattice constant from the XRD result, t is the thickness of the pore wall, and r is the density of the pore wall, which is assumed to be 2.2 g mL ±1.The thickness of the pore wall, t, can be obtained as a constant value of 0.9 nm from the plot of W 0 as a function of a. The pore diameter, d, can be estimated as a±t. b) M. Hruk, M. Jaroniec, A. Sayari, J. Phys. Chem. B, 1997, 101, 583. [17] S. Inagaki, A. Koiwai, N. Suzuki, Y. Fukushima, K. Kuroda, Bull. Chem. Soc. Jpn. 1996, 69, 1449 A Multi-Addressable Photochromic 1,2-Dithienylcyclopentene-Phenoxynaphthacenequinone Hybrid** By Andrew J. Myles, Tony J. Wigglesworth, and Neil R. Branda*The current interest in miniaturizing the components of machinery and electronics down to the molecular level is a major impetus to developing molecular systems that display switchable properties.[1] Photochromic compounds exhibit reversible variations in their physical characteristics when stimulated by light [1,2] and are some of the best contenders for use in electro-optical devices and memory media, where each isomer of the photochromic compound can represent ª0º or ª1º of a digital code. [3] One key aspect in the progress of molecular switching technology is the development of more complex systems that integrate several switchable functions into a single molecule. Memory media capable of processing more than two pieces of information at the same storage site is an illustrative example of an application of the use of multi-addressable switching strategies. Several impressive examples of multi-addressable switching systems have been reported with as many as six addressable states existing within the same molecule.[4] However, their practical application is limited due to the thermal reversibility of the switching units in almost all cases, the inability to access all states in most cases, and the fact that addition of chemical reagents is often required. A thermally stable, multi-addressable, all-photon mode system is more desirable as it will benefit from the fast response times and the ease at which monochromatic light can be tuned and focused when it is used as the switching stimulus. Few of the photochromic compounds known today display the favorable properties of 1,2-dithienylcyclopentene derivatives (DTE). These compounds undergo the thermally irreversible photochemical cyclization reactions (DTE-o > DTE-c) illustrated in Scheme 1, with a high degree of fatigue resistance, making them the most promising candidates for molecular read/write systems.[5] Scheme 1 also presents the photochromic phenoxynaphthacenequinone (PNQ) motif, which interconverts between its trans-(PNQ-t) and ana-forms (PNQ-a), also with a high level of thermal irreversibility and fatigue resistance. [6] We present here an all-pho...

Reversible and Amplified Fluorescence Quenching of a Photochromic Polythiophene

“…The particular DTE derivative was chosen based on predictions that the absorption and emission spectra of both components would meet two key criteria: (1) the absorption band for the polythiophene must lie in the narrow window where both isomers of the DTE are transparent so the polymer can be independently photoexcited; and (2) the emission from the polymer must overlap with the absorption band of only one of the DTE isomers, allowing fluorescence quenching through energy transfer. These predictions were made by examining the electronic spectra of DTE derivative 4 in its ring-open and ring-closed states [21] and, as will be demonstrated later in this report, both criteria are satisfied by P1o/P1c. The DTE-functionalized polythiophene P1o is prepared via a Huisgen 1,3-dipolar cycloaddition (''click'') reaction [22] between azide-polythiophene P3 and dithienylethene derivative 5, [21] as shown in Scheme 1.…”

“…These predictions were made by examining the electronic spectra of DTE derivative 4 in its ring-open and ring-closed states [21] and, as will be demonstrated later in this report, both criteria are satisfied by P1o/P1c. The DTE-functionalized polythiophene P1o is prepared via a Huisgen 1,3-dipolar cycloaddition (''click'') reaction [22] between azide-polythiophene P3 and dithienylethene derivative 5, [21] as shown in Scheme 1. [23] The key polymer starting material, P3, is obtained from bromide P2, which is prepared by copolymerizing 2,5-dibromo-3-(2-bromoethyl)thiophene and 2,5-dibromo-3-hexylthiophene using the nickel-catalyzed Grignard metathesis (GRIM) method.…”

Synthesis and Photochromic Behavior of Bi-functional Photochromic Compound

“…Photochromic compound is characterized by the ability to undergo a reversible transformation between two different chemical forms having different absorption spectra in response to light of appropriate wavelength [1][2][3][4]. One of the most widely studied classes of photochromism is the intense absorption of the colored form in the visible region, which is of great importance for practical applications of photochromic compounds.…”

Photo‐/Baso‐Chromisms and the Application of a Dual‐Addressable Molecular Switch

“…Despite these efforts, there are still some challenges, e.g., the difficulty in synthesis andt he independent controlo ft he differents witching units in single molecule. [16] In general, most of the multi-addressable molecular switches are achievedb y linking two individual switches with non-covalent [21][22][23][24][25][26][27] or covalent [28][29][30][31][32] bonds (Scheme 1a). However,s witching motifs with fewer and simpler units are more beneficialf rom the point of atomic efficiency.…”