Multifunctional Luminescent Sensor Based on the Pb²⁺ Complex Containing a Tetrazolato Ligand

Abstract

5), and [Pb(L 4 )(H 2 O) 2 ] (6) have been synthesized by treatment of polydentate tetrazolato ligands with various hydrated Pb 2+ salts (HL 1 = 2-(1H-tetrazol-5-yl)pyridine, HL 2 = 3-(1H-tetrazol-5-yl)isoquinoline, HL 3 = 6-(1H-tetrazol-5-yl)-2,2′-bipyridine, and H 2 L 4 = 6,6′bis(1H-tetrazol-5-yl)-2,2′-bipyridine). These complexes have been characterized by IR, TGA, and elemental analysis. Their crystal structures have been determined by X-ray crystallography, and the phase purity of bulk samples were further confirmed by PXRD. Their luminescence properties have been investigated in detail, and their emission origin may involve ligand-centered π−π* transition, metal-centered s-p transition and charge-transfer character. It is interesting to note that 5 exhibits obviously enhanced red-shifted emission, whose photoluminescence quantum yield (PLQY = 16.5%) is much higher than the other compounds (≤2%). Most importantly, the emission property of 5 was strongly affected by temperature. When the temperature rises from 295 to 493 K, the emission maximum gradually shifts to high energy due to the loss of the aqua ligand. In contrast, when the temperature is lowered from 295 to 13 K, two emission bands were observed. The low-energy emission band exhibits a slight blue shift, while a new high-energy emission band appears at around 520 nm, which is assigned to ligand-centered phosphorescence. After removal of the coordinated aqua ligand, the emission of 5−H 2 O is very sensitive to the vapors of volatile primary amines and acids, although they have different response mechanisms. This result indicates that 5−H 2 O may be a potential multifunctional sensor for temperature, volatile amines, and acids. To decipher the emission origin, DFT calculations have also been carried out based on the structure units of these compounds.

Efficient, Multicolored, and Stable Room‐Temperature Phosphorescence Doped Materials Based on a Lead Halide Matrix: A Coordination‐Driven Doping Strategy

“…The lifetime of NABA‐1%/PCB is up to 123.89 ms. As far as we know, they have not only the highest RTP efficiencies, but also longest lifetime among the non‐perovskite lead halide materials reported so far. [ 43–49 ] This PL QY is also comparable to or even better than the reported RTP DSs based on weak interactions (hydrogen bond, π – π stacking) or covalent bond (Table S5, Supporting Information). The above results prove that inorganic‐organic hybrid material matrix and coordination‐driven doping have unique advantages in preparing doped RTP materials.…”

“…[42] Some nonperovskite RTP lead halides overcome the problem of poor stability, but they suffer from low phosphorescence quantum yield, short lifetime, and single RTP color. [43][44][45][46][47][48][49] Therefore, it is crucial to develop lead halides with high stability and efficiency, longlived, and multicolor RTP.…”

Excited state energy landscape of phosphorescent group 14 complexes

“…50 The molecular congener V with 6,6 ′ -bis(1H-tetrazol-5-yl)-2,2 ′ -bipyridine as proligand shows 3 MLCT phosphorescence with signicantly lower photoluminescence quantum yield in the solid state (l p = 593 nm, s p = 347.5 ms, F p = 0.02; Scheme 1d). 50 Substituting a chlorido ligand with a weakly coordinating triato (OTf − ) ligand, increases the uorescence quantum yield of a dipyrromethene tin(II) complex from 0.04 (VI Cl ) to 0.42 (VI OTf ) with a slight bathochromic shi of the uorescence from l f = 518 nm to l f = 524 nm (Scheme 1e). 51 The signicant increase in quantum yield is ascribed on the basis of an inspection of the GS molecular orbitals from density functional theory (DFT) calculations to a shi of a non-photoluminescent MLCT state to higher energies upon stabilising the occupied non-bonding tin-centered orbital aer Cl − /OTf − exchange.…”

“…The photoluminescence lifetimes amount up to s p = 1.55 ms and a maximum quantum yield of F p = 0.165 in the solid state. 50 The molecular congener V with 6,6 ′ -bis(1H-tetrazol-5-yl)-2,2 ′ -bipyridine as proligand shows 3 MLCT phosphorescence with signicantly lower photoluminescence quantum yield in the solid state (l p = 593 nm, s p = 347.5 ms, F p = 0.02; Scheme 1d). 50 Substituting a chlorido ligand with a weakly coordinating triato (OTf − ) ligand, increases the uorescence quantum yield of a dipyrromethene tin(II) complex from 0.04 (VI Cl ) to 0.42 (VI OTf ) with a slight bathochromic shi of the uorescence from l f = 518 nm to l f = 524 nm (Scheme 1e).…”

Dual stimuli-responsive phosphorescence of a Pb(ii) coordination polymer to acidic vapors and thermal treatment

“…To date, there are only a few reports on luminescent Pb( ii ) CPs that can respond to more than one external stimulus. 18,19 To fabricate a new multistimuli-responsive luminescent Pb( ii ) CP, conjugated unsymmetrical 5-(3-pyridyl)-1,3,4-oxadiazole-2-thiol (Hpzt) has been exploited as a luminophore ligand incorporating with the Pb( ii ) center. The O, N, and S-heteroatoms containing Hpzt are not only the donor atoms for coordination assembly or the active sites for other chemical reactions but they also efficiently cause noncovalent intermolecular interactions, endowing CPs with interesting properties such as luminescence sensing and soft crystalline character.…”