π-Expanded Ketocoumarins as Efficient, Biocompatible Initiators for Two-Photon-Induced Polymerization

Abstract

A series of π-expanded coumarins comprising of 4–5 conjugated rings were designed and synthesized. The strategic placement of two dialkylamino groups containing long alkyl chains attached to the peripheral ends of bis-coumarins resulted in dyes with superb solubility. As α,β-unsaturated ketones, these compounds display properties of donor–acceptor–donor (D–A–D)-type chromophores. Photophysical studies of the new functional dyes revealed a combination of favorable properties: strong absorption of blue and green light, weak fluorescence, reasonable two-photon absorption (2PA) cross-section, and complete solubility in nonpolar solvents. The fluorescence lifetimes of coumarin-derived α,β-unsaturated ketones were measured for the first time. The placement of two amine groups at peripheral positions of the dyes produced two-photon absorption cross-section values at the level of 150–400 GM around 800 nm, which generated two-photon photoinitiation. The highest 2PA cross-section was approximately 400 GM for the derivative of 4-methylcyclohexanone. Directly using these compounds as sensitizer or initiator, two (2D)- and three-dimensional (3D) nanopatterns were successfully fabricated by two-photon initiated polymerization. 3,3′-Carbonyl-biscoumarin, which contains two dihexylamino substituents at positions 7 and 7′ possesses the largest fabrication window. MC3T3-E1 preosteoblastic cells exhibited strong adherence to all π-expanded coumarins and the same spindle-shaped morphology as the tissue culture treated polystyrene control surface. Additionally, our results showed an increase in cell proliferation after 3 and 7 days in culture, as well as a high cell viability of approximately 100% on all materials compared to the control surface. These findings confirm that D–A–D-type ketocoumarin derivatives used as potential photoinitiators are noncytotoxic and can be used in the fabrication of biomaterial scaffolds for tissue engineering applications.

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.…”

Synthesis and Optical Properties of α,β‐Unsaturated Ketones Bearing a Benzofuran Moiety

“…Consequently, three different cyclic ketones, namely cyclopentanone ( 7 ), 4‐methylcyclohexanone ( 8 ), and tetrahydropentalene‐2,5‐dione ( 9 ), and two 1,3‐diketones were selected as key building blocks, which allowed us to obtain dyes of different rigidity. The key building block, formylbenzofuran 2 , was prepared from corresponding aldehyde 1 in 64 % yield using a classical strategy (Scheme ). Aldehyde 2 was subsequently condensed with dimedone ( 3 ), indene‐1,3‐dione ( 4 ), cyclopentanone ( 7 ), 4‐methylcycloxanone ( 8 ), and tetrahydropentalene‐2,5‐dione ( 9 ) .…”

“…Dry column vacuum chromatography (DCVC) was performed for purification of products using silica gel Type D 5F. Compound 1 was obtained using methods already reported in the literature …”

Self-assembly of a series of thiocyanate complexes with high two-photon absorbing active in near-IR range and bioimaging applications

“…The research for functionalized materials with large molecular 2 PA cross sections (s) has mushroomed because of their potential applications in two-photon excitation fluorescence microscopy [1e8], microfabrication [9,10], laser up-conversion [11e15], optical power limiting [16e18], three-dimensional (3D) fluorescence imaging [19e21], optical data storage [22e25], photodynamic therapy [26,27], two-photon fluorescent probe, and so on. Among these applications, bioimaging as two-photon fluorescence probes in living cells has recently been received much attention [28e30] due to the fact that among various conventional bio-imaging techniques, two-photon excitation microscopy is a highly sensitive and noninvasive tool particularly for living cell and tissue imaging.…”