Synergetic Spin-Crossover and Luminescent Properties in a Multifunctional 2D Iron(II) Coordination Polymer

Abstract

We designed and synthesized a strong fluorescent tetradentate pyridine ligand, 3,6,11,12-tetra(pyridin-4-yl)dibenzo[a,c]phenazine (TPDP), by covalently grafting pyridyl to fluorescent dye dbpz, which can react with the Fe(NCX)2 (X = S and Se) unit, obtaining two new 2D [4 × 4] square-grid compounds, namely, {FeII(TPDP)2(SCN)2·CHCl3·4CH3OH} n (1) and {[FeII(TPDP)2(SeCN)2]·CH2Cl2·4CH3OH} n (2). Both of them show expected one-step spin-crossover (SCO) properties, and complex 2 vacuum exhibits a combination of the SCO phenomenon and fluorescence in a synergetic way. The energy transfer mechanism of 2 vacuum is verified by the theoretical calculations and experimental results. This study provides an effective strategy to synthesize large conjugated fluorescent ligands using dyes to further form SCO-luminescent bifunctional materials.

Naphthalimide-Tagged Iron(II) Spin Crossover Complex with Synergy of Ratiometric Fluorescence for Thermosensing

“…On the other hand, temperature-dependent intensity at 408 nm shows an “ s ” shape, which can be attributable to the typical effect by the SCO behavior. , According to Scheme , the ligand emission in SCO complex 1 may arise from both Fe LS –L* and Fe HS –L* excited states, i.e., I HS and I LS . Applying the Doman model of the SCO effect, the I 408 can be expressed by eq (Supporting Information in details). I 408 = false( I normalH normalS − I normalL normalS false) 1 + exp ( n Δ H R ) ( 1 T − 1 T 1 / 2 ) + I normalL normalS Both I HS and I LS invoked Mott–Seitz eq (eq ).…”

Spin-crossover tuning of the luminescence in 2D Hofmann-type compounds in bulk and exfoliated flakes

“…Previous reports of multifunctional luminescent SCO compounds are based on discrete complexes [5][6][7][8] or coordination polymers (CPs). [9][10][11][12][13][14][15] A remarkable family of SCO CPs are Hofmann-like compounds of formula [Fe II (L) x M(CN) y ] constructed by the equatorial coordination of tetracyanometallates ([M II (CN) 4 ] 2À with M = Pt, Pd or Ni) and the axial coordination of aromatic N-donor ligands (L), where L can be unidentate or bidentate bridging ligands to build 2D or 3D coordination networks, respectively. This family of compounds exhibits cooperative SCO, which can be modulated by a rich host-guest chemistry.…”

“…Previous reports of multifunctional luminescent SCO compounds are based on discrete complexes 5–8 or coordination polymers (CPs). 9–15…”

Manipulating fluorescence by photo-switched spin-state conversions in an iron(ii)-based SCO-MOF

“…[27][28][29][30][31] Recent studies have proven that the uorescence intensity of SCO complexes can be effectively modulated by spin-state conversions. [32][33][34][35][36][37][38][39] The uorophore acts as a photosensitizer responsible for absorbing photons and emitting uorescence, while the SCO unit is a better energy acceptor. When a coupling path is built between them, the energy transfer efficiency from the uorophores to metal ions will be different for the HS and LS states due to the varied overlaps of emission bands of the ligand and absorption bands of the metal ion.…”