ABSTRACT
Just as the heterojunctions in physics, donor-acceptor (D-A) heterostructures are an emerging class of photoactive materials fabricated from two semiconductive components at the molecular level. Among them, D-A hybrid heterostructures from organic and inorganic semiconductive components have attracted extensive attention in the past decades due to their combined advantages of high stability for the inorganic semiconductors and modifiability for the organic semiconductors, which are particularly beneficial to efficiently achieve photoinduced charge separation and transfer upon irradiations. In this review, by analogy with the heterojunctions in physics, a definition of the D-A heterostructures and their general design and synthetic strategies are given. Meanwhile, the D-A hybrid heterostructures are focused on and their recent advances in potential applications of photochromism, photomodulated luminescence, and photocatalysis summarized.
ABSTRACT
The self-assembly of electron-deficient protonated N, N'-dipyridyltetrachloroperylenediimide (4Cl-DPPDI) and electron-rich polyoxometalate acids HnXM12O40 (POMs; X = P or Si; M = W or Mo) resulted in four isomorphous donor-acceptor hybrid crystals 1-4 with segregated POM anions and one-dimensional racemic hydrogen-bonded 4Cl-DPPDI networks as electron-donor and -acceptor components, respectively. Because of the compact contacts between the POM anions and 4Cl-DPPDI tectons induced by anion-π interactions, besides enhanced photochromism, these four unique isostructural hybrids exhibited unusual room-temperature phosphorescence (RTP) emissions. More interestingly, owing to the facial compact contacts of two racemic 4Cl-DPPDI tectons induced by lone pair-π-assisted π-π interactions, they also showed unprecedented photon upconversion by triplet-triplet annihilation (TTA).
ABSTRACT
Donor-acceptor (D-A) hybrid crystals are an emerging kind of crystalline hybrid material composed of semiconductive inorganic donors and organic acceptors. Except for the intrinsic photochromism, recently we have reported that the anion-π polyoxometalate (POM)/naphthalenediimide (NDI) hybrid crystals could produce an interesting room temperature phosphorescence (RTP) quantum yield up to 7.2%. Herein, we extended into core-substituted NDIs and anticipated the regulation of their photochromic and RTP properties. Thus, two hybrid crystals, namely (H4BDMPy-Br2NDI)·(NMP)4·(HPW12O40) (1) and (H4BDMPy-I2NDI)·(HPW12O40) (2) (H2BDMPy-Br2NDI: N,N'-bis(3,5-dimethylpyrazolyl)-2,6-dibromo-1,4,5,8-naphthalenediimide and H2BDMPy-I2NDI: N,N'-bis(3,5-dimethylpyrazolyl)-2,6-diiodide-1,4,5,8-naphthalenediimide), have been synthesized from phosphotungstic anions (PW12O403-) and Br or I core-substituted NDIs. Compared to the core-unsubstituted analogues (H4BDMPy-NDI)·(NMP)4·(HPW12O40) (3), 2 with photosensitive iodine substituents is more sensitive to light, which can become discolored under natural light. As a result of the heavy-atom effect, hybrid 1 exhibits remarkable RTP with the quantum yield up to 10.2% and a lifetime of 1.14 ms.
ABSTRACT
D-A hybrid heterostructures are an emerging class of crystalline hybrid materials composed of semiconductive inorganic donors and organic acceptors. However, due to the steric effects of the inorganic coordination sites, it is difficult for the large organic molecules to form compact packing at the molecular level, resulting in the poor efficiency of photoinduced charge transfers. To achieve an effective carrier separation and transfer, herein we incorporated third donors into a copper(I) halide/thiazolo[5,4-d] thiazole D-A heterostructure to construct three novel three-component complexes (Me2-Py2TTz)Cu4I6·(I2) (1), (Me2-Py2TTz)Cu3I5·(pyrene) (2) and (Me2-Py2TTz)Cu3I5·(perylene) (3) (Py2TTz = 2,5-bis(4-pyridyl) thiazolo[5,4-d] thiazole), respectively. Due to the spatial distances as well as the orbital energies between the copper(I) halide and thiazolo[5,4-d] thiazole units bridged by third donors, they are excellent three-component charge-transfer complexes (CTCs) with enhanced electrical properties.
ABSTRACT
The incorporation of photochromic moieties into coordination polymers is of particular interest because it can endow them with various switching functions such as electrical conductivity, luminescence, and magnetism. In this context, a viologen ligand as a photochromic moiety was incorporated into 3d-4f heterobimetallic hexacyanoferrates, resulting in three novel 3-D photochromic complexes with different metal cations, namely {[Ln(BCEbpy) M(CN)6 (H2O)4]·2H2O}n (denoted as CoDy, CoEu, and FeDy, Ln = Dy, Eu; M = Fe, Co, H2BCEbpy·2Br = N,N'-bis(carboxymethyl)-4,4'-bipyridinium dibromide). And the photoresponsive mechanism has been well discussed based on the solid UV-vis, IR, ESR, photoluminescence, and magnetism data. Moreover, accompanying the photochromic process, these unique complexes exhibit different photomagnetic behaviors upon UV-vis irradiation at RT because of the different ferromagnetic coupling interactions between photogenerated radicals and lanthanide cations.
ABSTRACT
As an emerging class of hybrid complexes, donor-acceptor (D-A) hybrid heterostructures with advantages of both photoactive organic and inorganic components have provided an excellent platform for the fabrication of multifunctional photoactive materials. In this context, we have demonstrated three novel host-guest D-A hybrid heterostructures, {[Ln(BCEbpy)(H2O)4][CoIII(CN)6]·4H2O}n (1 (Eu), 2 (Dy), 3 (Sm)), based on the anionic Co(CN)63- and cationic coordination layers assembled from a viologen functionalized tecton and Ln(NO)3. Due to the introduction of an electron donor, CoIII(CN)63-, the unique hybrid exhibits a highly sensitive and reversible photochromic transformation from light-yellow to brown upon UV-Vis irradiation. More interestingly, accompanied with this photochromic process, hybrid 1 simultaneously possesses a photomodulated fluorescence behaviour. In addition, hybrid 1 shows high sensitivity and selectivity towards Cr2O72- anions with a fairly small LOD of ca. 9.6 × 10-6 M.
ABSTRACT
D-A hybrid heterostructures are an attractive class of hybrid complexes composed of semiconducting organic and inorganic components, which make them potential candidates for applications in the photoelectric fields, particularly as photochromic materials. Herein, we report that the combination of metal cations (M = Zn2+ or Cd2+), silicomolybdic anions, and N,N-di(4-pyridyl)-1,4,5,8-naphthalene diimide (DPNDI) via two diffusion methods (A and B) led to four three-component D-A hybrid heterostructures with silicomolybdic anions as electron donors, and one-dimensional (1-D) naphthalenediimide coordination networks of different metal cations, [Zn2(DPNDI)2(H2O)4]·(SiMo12O40) (1-A and 1-B) and [Cd2(DPNDI)2(H2O)4]·(SiMo12O40) (2-A and 2-B), as electron acceptors. Although the different diffusion methods, 1-B, 2-A and 2-B, are isostructures with close cell parameters. Due to the different ionic radii and electronegativity of metal cations in isostructural 1-B and 2-B, they exhibit different electron-transfer photochromic behaviors. This study paves a new path for designing novel photochromic materials through such third-component metal cations.
ABSTRACT
Donor-acceptor (D-A) hybrid heterostructures are an emerging class of hybrid complexes with potential applications in current optoelectronic technologies. To achieve high photoinduced charge-carrier generation and separation in a heterostructure, a common strategy is the fabrication of continuous or bicontinuous structures by the crystallization of semiconductive donor and acceptor tectons at the molecular level. So far, only a few such heterostructures have been fabricated, most of which involve unstable and narrow band gap metal halides. In this paper, we extended these unique hybrid heterostructures to continuous alkaline-earth metal oxide clusters. The combination of the naphthalene diimide (NDI) tecton bearing four carboxylates at two extremities with Ca2+ (or Sr2+) cations led to two isostructural D-A hybrid heterostructures with infinite 1-D carbon-doped alkaline-earth metal oxide clusters and X-aggregated NDI dimers as electron donors and acceptors, respectively. Due to the different metal cations in inorganic clusters, they exhibited diametrically opposite photochromic sensitivities and photocatalytic activities. To better rationalize them, a plausible photoinduced electron transfer process for the D-A hybrid heterostructures with photoactive acceptors has been developed.
ABSTRACT
The asymmetric unit of the title complex, {[Cd2(C10H10N3O3S)2(C10H8N2)(NO3)2]·4C3H7NO} n , consists of one Cd(II) cation, one N-[2-(2-hy-droxy-benzo-yl)carbamo-thio-yl]acetamidate ligand, half a 4,4'-bipyridyl ligand, one coordinating nitrate anion and two di-methyl-formamide solvent mol-ecules of crystallization. The bipyridine ligand is completed by inversion symmetry. The metal cation exhibits a distorted penta-gonal-bipyramidal coordination geometry provided by two O and one N atoms of the thio-semicarbazide ligand, two O atoms of the nitrate anion, one S atom of a neighbouring thio-semicarbazide ligand and one 4,4'-bi-pyridine N atom. The bridging role of the thio-semicarbazide ligand through the S atom leads to centrosymmetric binuclear units, which are further linked by 4,4'-bi-pyridine units, forming polymeric chains extending along the b-axis direction. An intra-molecular N-Hâ¯O hydrogen bond occurs. The crystal structure also features N-Hâ¯O and O-Hâ¯O hydrogen bonds, leading to the formation of a three-dimensional network.