A Two‐Dimensional Iron(II) Coordination Polymer with Synergetic Spin‐Crossover and Luminescent Properties

Abstract

A composite material, {[Fe(L)(TPPE)0.5]⋅3 CH3OH}n, has been constructed by integrating the spin‐crossover (SCO) subunit FeII{diethyl(E,E)‐2,2′‐[1,2‐phenyl‐bis(iminomethylidyne)]bis(3‐oxobutanoate)‐(2‐)‐N,N′,O3,O3′} and the highly luminescent connector 1,1,2,2‐tetrakis(4‐(pyridin‐4‐yl)phenyl)‐ethene. Its structure contains four staggered 4×4 layers and intercalated methanol. The packing is dominated by considerable H‐bonds either between adjacent layers and between layers and guests. A crystal‐structure transformation was detected upon removal of the guest molecules. The SCO transition of the solvated crystals is centered at ca. 215 K with a non‐symmetrical hysteresis of 25 K wide, and the desolvated [Fe(L)(TPPE)0.5]n exhibits gradual SCO without hysteresis. Intriguingly, the intensity of the fluorescence at 460 nm for the latter is maximized at the SCO transition. The energy transfer between luminescent and SCO entities is achievable as confirmed by theoretical calculations.

Sublimable Spin‐Crossover Complexes: From Spin‐State Switching to Molecular Devices

“…In this regard, it is desirable to design SCO complexes with an additional physical property, thus functional‐SCO complexes, which could be sublimed onto a suitable substrate with preservation of switching characteristics. Functional‐SCO complexes tailored with organic semiconductors, [169] photoluminescent substituents, [170–173] and self‐assembly‐inducing moieties [105, 174] are proposed. The high resistance of organic molecules is a bottleneck for the realization of active molecular electronic components for applications.…”

Sublimierbare Spin‐Crossover‐Komplexe: Vom Schalten des Spinzustands zu molekularen Bauelementen

“…In diesem Zusammenhang wäre es wünschenswert, SCO‐Komplexe mit einer weiteren physikalischen Eigenschaft auszustatten, also schaltbare SCO‐Funktionskomplexe herzustellen, die auf ein geeignetes Substrat sublimiert werden könnten. Vorgeschlagen wurden die Funktionalisierung von SCO‐Komplexen mit organischen Halbleitern, [169] Photolumineszenz‐Substituenten [170–173] oder Elementen, die die Selbstorganisation fördern [105, 174] . Für die Herstellung von aktiven molekularen elektronischen Komponenten erweist sich der hohe Widerstand von organischen Molekülen als kritischer Punkt.…”

Coexistence of luminescence and spin-crossover in 2D iron(ii) Hofmann clathrates modulated through guest encapsulation

“…Although other types of 2D coordination polymers presenting synergies between luminescence and SCO have been recently reported, [62][63][64] up to date only one example of fluorescent 2D Fe II -HCPs is known. 65 The interest of these laminar 2D Fe II -HCPs resides in the possibility of adjusting the layer-to-layer space designing interlayer cavities where a wide range of functional guests can actuate in synergy with both the SCO and fluorescence properties.…”