Molecular Split-Ring Resonators Based on Metal String Complexes

Abstract

Metal string complexes or extended metal atom chains (EMACs) belong to a family of molecules that consist of a linear chain of directly bonded metal atoms embraced helically by four multidentate organic ligands. These four organic ligands are usually made up of repeating pyridyl units, single-nitrogen-substituted heterocyclic annulenes, bridged by independent amido groups. Here, in this paper, we show that these heterocyclic annulenes are actually nanoscale molecular split-ring resonators (SRRs) that can exhibit simultaneous negative electric permittivity and magnetic permeability in the UV-Vis region. Moreover, a monolayer of self-assembled EMACs is a periodic array of molecular SRRs which can be considered as a negative refractive index material. In the molecular scale, where the quantum-size effect is significant, we apply the tight-binding method to obtain the frequency-dependent permittivity and permeability of these molecular SRRs with their tensorial properties carefully considered.Comment: 8 pages, 8 figure

From Homonuclear Metal String Complexes to Heteronuclear Metal String Complexes

“…[61] According to a simple tight-binding calculation, these supporting ligands are considered as nanoscale molecular split-ring resonators (SRRs) and can exhibit simultaneous negative electric permittivity and magnetic permeability in the UV/Vis region. [62] McGrady et al addressed the relationship between the structure and transport phenomena of metal string complexes by analysis of their conduction channels. [27,44,48,[63][64][65][66] With the development of HMSCs, theoretical studies provide directions for the design of molecular rectifiers.…”

Broad-band negative refraction via simultaneous multi-electron transitions

“…Metamaterials with negative refraction [1][2][3][4][5][6][7] have attracted broad interest because of their potential applications, including perfect lenses [2,8], fingerprint identification in forensic science [9], simulating condensed matter phenomena and reversed Doppler effect [10,11], controlling light polarization [12], and electromagnetic cloaking [13][14][15]. In order to realize metamaterials, a number of routes have been proposed, including (molecular) split-ring resonators [3,16,17], chiral approaches [18], hyperbolic dispersion [19][20][21][22], dark-state mechanism [23][24][25][26][27], and topological routes [28][29][30]. However, none of these can effectively overcome the difficulty of realizing broad-band negative refraction.…”

A Chiral Macrocyclic Oligothiophene with Broken Conjugation – Rapid Racemization through Internal Rotation

“…[26] As an example, a negative refractive index at microwave frequencies was reported for a large array of equally micrometer sized metallic SRRs. [27] [28] The design of molecule 1 (Figure 1) combines the conjugated periphery of an oligothiophene macrocycle with the conjugation altering pseudo-para [2.2]paracyclophane (PC). Using again the inspiring picture of a SRR, the macrocycle consisting of 2,5-interlinked thiophenes represent the 'ring', while the PC acts as the 'split'.…”