Synthesis and Properties of New Chiral Donor-Embedded Polybinaphthalenes for Nonlinear Optical Applications

Abstract

8 new chiral, chromophore-functionalized donor-embedded polybinaphthalenes were prepared and characterized for their (nonlinear) optical properties. The polymers were prepared by direct polymerization using a Stille coupling reaction between a chiral bis(trimethyltin) binaphthalene derivative and diiodo-functionalized chromophores. The use of diiodo-functionalized instead of dibromo-functionalized chromophores resulted in a significant increase of molecular weight, as demonstrated by end-group analysis, GPC and MALDI-TOF experiments. The reaction conditions allowed the use of a great variety of chromophores with different DπA-structures. The typical treelike macromolecular architecture of the polymers is reflected in the behavior of the glass transition temperature and, more clearly, in the nonlinear optical properties. The nonlinear optical response shows a continuous, linear increase in function of chromophore concentration, indicating that the dipolar interactions between the chromophores are eliminated. Moreover, chiral contributions to the nonlinear optical response were observed and mounted 14 % of the highest achiral contribution.

Donor‐Embedded Polybinaphthalenes for Nonlinear Optical Applications: Influence of the Incorporation of a Double Bond

“…Compound 1 and chromophores a and b (Scheme 1) were synthesized according to the literature procedures. [1] Synthesis of (R)-(-)-2,2 0 -dihexyloxy-[1,1 0 -binaphthyl]-6,6 0 -dicarbaldehyde (2) A solution of 1 (5.00 g, 8.00 mmol) in dry THF (80 mL) was cooled to À78 8C and purged with argon. After 15 min butyllithium (17.6 mmol, 2.5 M in hexane) was added.…”

“…This tree-like supramolecular architecture, the chromophores (branches) are attached to a rigid backbone (trunk), diminishes and even excludes dipolar interactions between the chromophores. [1] Therefore, these systems allow a very high chromophore density, which cannot be obtained in random coil polymers. [1] Second, chiral donorembedded polybinaphthalenes can benefit from contributions, inherently to chirality, which can increase the NLO response.…”

“…[1] Therefore, these systems allow a very high chromophore density, which cannot be obtained in random coil polymers. [1] Second, chiral donorembedded polybinaphthalenes can benefit from contributions, inherently to chirality, which can increase the NLO response. [2] In a previous study on donor-embedded polybinaphthalenes, [1b] it was demonstrated that they are a very interesting class of polymers since (1) the dipolar interactions between the chromophores are excluded in these Summary: In this paper two new donor-embedded polybinaphthalenes prepared by the Heck reaction are presented.…”

Synthesis of Binaphthyl-Based Push-Pull Chromophores with Supramolecularly Polarizable Acceptor Ends

“…On the other hand, molecular chirality offers simple design principles for push-pull and noncentrosymmetric molecules, and the nanostructuring via self-assembly of chiral organic dyes has been shown to have pronounced effects and amplifications of their SHG response [9]. Binaphthyl compounds have been exploited for the realization of second-order nonlinear optical (NLO) materials, having the combined advantages of being chromophores and carrying the required element of chirality for bulk anisotropy [10][11][12][13][14][15][16][17]. In fact, binaphthyl systems, such as that shown in Figure 1, are composed of two chromophores joined through an aryl-aryl bond, which is the element (axis) of chirality, with dihedral angles usually close to 90 ∘ , so that interchromophoric conjugation is not efficient.…”

“…The application of the binaphthyl compounds in the field of nanosciences is recent and not yet fully explored [18][19][20][21][22][23][24][25][26][27][28][29]. In all previously reported examples of binaphthyl dyes for NLO applications, the molecular design expressing the push-pull concept was developed by placing electron donating groups in the 2,2 positions and the electron accepting units in the 6,6 positions ( Figure 1) [10][11][12][13][14][15][16][17].…”