Characterisation of N‐(Octadecyl)‐1,8‐naphthalimide Monolayer Compression Using Molecular Dynamics and Experimental Approaches

Abstract

The development of luminescent surfaces is an active area of supramolecular chemistry, particularly for the development of new sensing platforms. One particularly useful surface deposition method is the Langmuir–Blodgett technique where organic amphiphilic fluorophores (e.g. 1,8‐naphthalimides) can form ordered monolayers at an air–water interface before being deposited onto solid supports. The ability to simulate monolayer formation and consequently develop predictability over film formation would allow for significant advances in the luminescent materials field where synthesis might be directed by simulation data. Here, we compare pressure‐area isotherms of N‐(octadecyl)‐1,8‐naphthalimide determined experimentally, using the Langmuir–Blodgett technique, and computationally, using three different simulation techniques. We find that all three simulation techniques are able to describe the liquid‐condensed/liquid‐expanded region of the isotherm, and that the isotherms are highly similar in this region, although the NγT ensemble performs best. Experimental isotherms showed film formation properties that align with the simulation data, suggesting that simulations are a viable means to direct synthesis. Investigation of the underlying structural details disclosed by the simulations reveals the compression‐induced ordering at atomic‐level detail, which will allow prediction of how functionalisation of the naphthalimides will alter the monolayer compression and mounting process.

Concentration-Dependent Effect of the Steroid Drug Prednisolone on a Lung Surfactant Monolayer

“…For this, conversion of eq 2 into eq 3 is carried out to calculate the surface pressure at corresponding APL values, as described in the literature. 47,52,53 (APL) (APL) CGMD aw eq π γ γ = * −…”

“…For this, a specific value for the surface tension of water, γ aw (see eq ), can sometimes be difficult due to CGMD force fields do not accurately reproduce the experimental value of γ aw . − While the quantitative reproduction of the π-APL isotherm at low surface tension remains challenging for the MARTINI and other models, qualitative trends of changes in APL are possible. ,, To reproduce the π-APL isotherm from simulations, the adoptive surface tension is used instead of pure water surface tension (γ aw ). For this, conversion of eq into eq is carried out to calculate the surface pressure at corresponding APL values, as described in the literature. ,, where γ aw * is effective surface tension that depends on the system size, simulation conditions, temperature, and γ eq (APL) is the surface tension from the simulation at corresponding APL. The term is the lateral pressure, P zz is the pressure tensor along the normal of the monolayer surface, and L z is the box height along the normal of the monolayer surface.…”