Two-photon absorption in host-guest complexes

Md Mehboob Alam,Kenneth Ruud

doi:10.1080/00268976.2020.1777335

Abstract

We present an extensive analysis of one- and two-photon absorption processes in some organic host-guest (H-G) complexes using linear and quadratic response theory within the framework of time-dependent density functional theory. For this purpose, we have considered all possible 20 host-guest complexes constructed from 4 host and 5 guest molecules. We have analysed how the one- and two-photon activity of the host and guest molecules are transferred to the respective host-guest complexes and how the electron donating and electron accepting ability of host-guest complexes affect their two-photon activity. Based on an analysis using the concept of channel interference, we have performed an in-depth analysis of the two-photon absorption processes in all these systems and provided a microscopic explanation for their variation among different complexes.

Highlights

The chemistry of host-guest systems, where two identical or different subsystems are held together and interact with each other in a non-covalent way, such as via van der Waals forces, hydrogen bonding, or π –π interactions, falls under the broad subject area of ‘supramolecular chemistry’ and ‘molecular recognition’ [1,2]
The host generally has a cavity-like space or a suitable space to hold another molecule, which is called the guest. Such systems are recognised in biology [3], where they are denoted as enzyme-receptor systems and/or lock-key system
In the present work we study the two-photon absorption (TPA) process in a number of host-guest complexes

Summary

Introduction

The chemistry of host-guest systems, where two identical or different subsystems (molecules/ions) are held together and interact with each other in a non-covalent way, such as via van der Waals forces, hydrogen bonding, or π –π interactions, falls under the broad subject area of ‘supramolecular chemistry’ and ‘molecular recognition’ [1,2]. In 2009, Chakrabarti and Ruud theoretically studied the two-photon absorption (TPA) process in the molecular tweezer-TNF host-guest system [27] They found that tweezer-TNF display a very large TPA cross-section as compared to the constituents. Questions such as how the nature of the host and guest molecules as electron donor and/or acceptor influences the overall molecular properties such as TPA has not yet been addressed To fill this gap, in the present work we study the TPA process in a number of host-guest complexes. We will study the role of the donor/acceptor nature of the host and guest molecules on the two-photon absorption (TPA) process in the resultant host-guest systems.

Computational details

Results and discussions

Few-state model analysis of TPA in the H-G complexes

Conclusions