Conjugates of thermally stable phthalocyanine J-type dimers with single-walled carbon nanotubes for enhanced optical limiting applications

•Created liquid and film materials for optical limiters are effective.•Chemical binding of nanotubes and phthalocyanines forms conjugates.•The presence of conjugates in materials increases non-linear absorption.•The dependence of the absorption on the intensity has a threshold character.•Nanosecond pulses are sharply attenuated, exceeding the threshold intensity. The widespread application of laser devices requires development of new protections against light pulses of high intensity. This problem is relevant because of the danger of hitting the civil aviation pilots with bright and powerful radiation originating from the laser sources which are widely used in the everyday life. Therefore, this work is devoted to continuing our research on a new class of macroheterocyclic compounds – thermally and chemically stable J-type phthalocyanine dimers as potential nonlinear absorbers for optical limiting technology. The dimeric complexes of magnesium (1a) and zinc (1b) were covalently bonded to single-walled carbon nanotubes (SWCNTs) to improve the overall characteristics of the potential optical limiters 2a,b as compared to the previously studied corresponding dyes in solutions. The conjugates obtained were investigated using atomic force microscopy (AFM), as well as Raman and IR spectroscopy to confirm formation of the covalent binding of phthalocyanine macrocycles with the carbon surface. Open-aperture Z-scan and a fixed limiter location experiments have demonstrated low values of the limiting threshold and high degree of attenuation of the input laser radiation with the pulses duration located in the nanosecond range.