π‐Expanded α,β‐Unsaturated Ketones: Synthesis, Optical Properties, and Two‐Photon‐Induced Polymerization

Abstract

A library of π-expanded α,β-unsaturated ketones was designed and synthesized. They were prepared by a combination of Wittig reaction, Sonogashira reaction, and aldol condensation. It was further demonstrated that the double aldol condensation can be performed effectively for highly polarized styrene- and diphenylacetylene-derived aldehydes. The strategic placement of two dialkylamino groups at the periphery of D-π-A-π-D molecules resulted in dyes with excellent solubility. These ketones absorb light in the region 400-550 nm. Many of them display strong solvatochromism so that the emission ranges from 530-580 nm in toluene to the near-IR region in benzonitrile. Ketones based on cyclobutanone as central moieties display very high fluorescence quantum yields in nonpolar solvents, which decrease drastically in polar media. Photophysical studies of these new functional dyes revealed that they possess an enhanced two-photon absorption cross section when compared with simpler ketone derivatives. Due to strong polarization of the resulting dyes, values of two-photon absorption cross sections on the level of 200-300 GM at 800 nm were achieved, and thanks to that as well as the presence of the keto group, these new two-photon initiators display excellent performance so that the operating region is 5-75 mW in some cases.

High-speed two-photon polymerization 3D printing with a microchip laser at its fundamental wavelength

“…1(a)). The usage of ketones as initiators of both single-and two-photon polymerization is ubiquitous [23][24][25][26]. The carbonyl group being one of the strongest electron-withdrawing groups, offers obvious advantages in the design of organic dyes possessing large two-photon absorption.…”

3D printing hybrid organometallic polymer‐based biomaterials via laser two‐photon polymerization

“…In most cases, the hybrid materials are rendered photosensitive by adding photoinitiators with high two‐photon absorption cross‐sections, either commercially available ones (e.g. Irgacure 2959, Irgacure 369 and Michler's ketone) or custom‐synthesized ones . Hybrid organic–inorganic materials such as those based on organometallic polymers are highly promising due to their versatility of applications and properties.…”

“…Irgacure 2959, Irgacure 369 and Michler's ketone) or custom-synthesized ones. [27][28][29][30][31] Hybrid organic-inorganic materials such as those based on organometallic polymers are highly promising due to their versatility of applications and properties. To date, organometallic materials incorporating Ge, 32 Ti, 33 V 34 and Zr 35 have been produced by LTPP.…”

Photoinitiators for two-photon polymerisation: effect of branching and viscosity on polymerisation thresholds

“…The development of photoinitiators (PIs) for two-photon polymerisation (TPP) has been an area of intense research for nearly two decades. [1][2][3][4][5] Many two-photon absorbing (2PA) materials have been developed in recent years to maximise 2PA cross-sections (d 2PA ), however oen neglected are key factors that make them more useful for TPP. [6][7][8][9][10] These include the need for low uorescence quantum yields (f F ) and solubility in pre-polymer resins.…”