Cooperative Action of Laser-Induced Thermal Effects and Ionic Coordination on the Order of TPPA0 Porphyrin Derivatives Self-Assembled Interface Probed via Real-Time Second Harmonic Generation

Abstract

We performed real-time second harmonic generation (SHG) to study the cooperative action of laser-induced thermal effects and ionic coordination on the order/disorder of TPPA0 (5,10,15,20-(tetrakis((ethoxycarbonyl)methoxy)phenyl)porphyrin) monolayers on the interface of three aqueous solutions. Time dependence curves of SH signals of TPPA0 monolayers on pure water and ZnCl 2 aqueous and CuCl 2 aqueous interfaces were detected under the polarization combinations of p-in/p-out, s-in/p-out and 45°-in/s-out. All the SH signals changed with time at the beginning and then reached the equilibrium state. For the pure water and ZnCl 2 aqueous interfaces, SH signals under the polarization of p-in/pout declined with time; while on the CuCl 2 aqueous interfaces, the SH signals raised with time. To explain the various change of the SH signals with time, we also measured these time dependence curves under the polarizations of the p-in/p-out, s-in/p-out, and 45°-in/s-out, all of which can be used to determine the orientation angle and corresponding orientation distribution width. It is found that the orientation angle with δ distribution cannot explain the ratios of the SH signal change; thus, the gauss orientational distribution width has to be considered instead of δ distribution, which means the TPPA0 monolayers undergone the change process of the orientational order until reaching equilibrium. Furthermore, using a rotating trough, the SH signals of TPPA0 monolayer on the three interfaces under the p-in/pout polarization are nearly unchanged during the measurement. These results indicated that all of the SH signal changes with time are induced by local accumulated heat with repetitive laser excitation at 82 MHz. At last, we propose a molecular mechanism to explain the changes of the SH signal on TPPA0 monolayers. The cooperative action of laser-induced thermal effects and the ionic coordination cause the signal change with time, which means the order of the porphyrin derivatives selfassembled interface is affected by the combination of ions and heat. The finding in this work is important to the bioscience, as well as the functional molecular devices.

In Situ Heterodyne-Detected Second-Harmonic Generation Study of the Influence of Cholesterol on Dye Molecule Adsorption on Lipid Membrane

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One-Fold Anisotropy of Silver Chiral Nanoparticles Studied by Second-Harmonic Generation

“…The interfacial chirality was characterized using a customized nonlinear SHG-LD setup based on a typically reflected geometry, as shown in Figure . − A broadband tunable mode-locked femtosecond (fs) Ti:sapphire laser (Tsunami 3960C, Spectra-Physics) was used with a pulse width of 80 fs and repetition rate of 82 MHz. The fundamental beam at a central wavelength of 800 nm was passed through a polarizer and a half-wave plate and then focused on the air/sample interface through an optical lens (with a focal length of 100 mm).…”

Metal Ion Mediation of Interfacial Chiral Supramolecular Formation of Amphiphilic Schiff Bases Studied by In Situ Second Harmonic Generation

“…The interfacial chirality of the monolayers was characterized using a customized nonlinear SHG-LD setup based on a typically reflected geometry. 25 The SHG-LD setup is briefly described as follows. A broadband tunable mode-locked femtosecond Ti:sapphire laser (Tsunami 3960C, Spectra-Physics) with a pulse width of 80 fs and a repetition rate of 82 MHz was used to produce the fundamental beam at a central wavelength of 800 nm.…”

“…The interfacial chirality of the monolayers was characterized using a customized nonlinear SHG-LD setup based on a typically reflected geometry . The SHG-LD setup is briefly described as follows.…”

“…They found that the chiral signal first increased and then decreased as the bulk concentration increased . Chiral and achiral SFG-VS have also been widely used to obtain the chirality and orientation information of amino acids and to study the interaction of peptides and proteins at lipid membranes. − …”