Knot-isomers of Moebius Cyclacene: How Does the Number of Knots Influence the Structure and First Hyperpolarizability?

TL;DR

This study systematically investigates how the number of knots in Moebius cyclacene molecules affects their structure and significantly enhances their first hyperpolarizability, revealing knots as a new means to boost nonlinear optical properties.

Contribution

It introduces the concept that adding knots to cyclacenes dramatically increases their first hyperpolarizability, providing new insights into molecular design for nonlinear optics.

Findings

Knot-isomers with knots have higher hyperpolarizability than without.

Introducing knots increases hyperpolarizability up to 13 times.

Knot number correlates with hyperpolarizability enhancement.

Abstract

Four large ring molecules composed by 15 nitrogen-substituted benzene rings, named as "knot-isomers of Moebius cyclacene", i.e. non-Moebius cyclacenes without a knot (0), Moebius cyclacenes with a knot (1), non-Moebius cyclacenes with two knots (2), and Moebius cyclacenes with three knots (3), are systematically studied for their structures and nonlinear optical properties. The first hyperpolarizability (beta_0) values of these four knot-isomers structures are 4693 (0) < 10484 (2) < 25419 (3) < 60846 au (1). The beta_0 values (60846 for 1, 10484 for 2 and 25419 au for 3) of the knot-isomers with knot(s) are larger than that (4693 au for 0) of the knot-isomer without a knot. It shows that the beta_0 value can be dramatically increases (13 times) by introducing the knot(s) to the cyclacenes structures. It is found that introducing knots to cyclacenes is a new means to enhance the first hyperpolarizability.