Crown-ether-substituted asymmetric phthalocyanine derivatives/CdS self-assembled hybrid films with an unprecedented high response toward NO2

Two asymmetrical amphiphilic phthalocyanines simultaneously containing hydrophobic alkoxy and hydrophilic 15-crown-5-ether substituents at the phthalocyanine periphery H2{Pc(15C5)3[(OC8H[Formula: see text]]}(Pc-1) and H2{Pc(15C5)[(OC8H[Formula: see text]]}(Pc-2) and their symmetrical analogue H2[Pc(OC8H[Formula: see text]] (Pc-3) have been synthesized and characterized. The Pc-n/CdS ([Formula: see text] 1, 2 and 3, respectively) hybrid films are obtained successfully via a simple quasi-Langmuir–Shäfer (QLS) method using H2S-vapor annealing over the Pc-n/Cd[Formula: see text] self-assembled film formed at the interface of the air/CdCl2 aqueous solution. The film-structure and properties of both the hybrid Pc-n/CdS and pure Pc-n films are comparatively studied by a wide range of methods including UV-vis, polarized UV-vis, XRD, SEM and I–V measurements. Experimental results exhibit a slipped co-facial stacking mode in an “edge-on” conformation ([Formula: see text]-type aggregate) formed for the phthalocyanine molecules in both pure Pc-n films and the corresponding Pc-n/CdS hybrid films, with increasing intermolecular [Formula: see text]–[Formula: see text] interactions in the order of Pc-n <Pc-n/CdS and Pc-3/CdS <Pc-2/CdS <Pc-1/CdS, respectively. Accordingly, film-microstructures, crystallinity and conductivity are effectively improved by introducing CdS nanoparticles into the 15-crown-5-substituented phthalocyanines forming Pc-1/CdS and Pc-2/CdS hybrid films. These render excellent sensing performance towards NO2 in the 0.05–2.5 ppm range within a fast dynamic exposure period of 30 s. Strikingly, Pc-1/CdS hybrid film presents an unprecedented high sensitivity of 157.3%.ppm[Formula: see text] vs. very low NO2 concentration range of 0.05˜0.25 ppm, achieving one of the best room temperature sensing performances in terms of high sensitivity, rapid responsibility and low detection limit among self-assembled film-based NO2 sensors.

Highly selective enzymatic-free electrochemical sensor for dopamine detection based on the self-assemblied film of a sandwich mixed (phthalocyaninato) (porphyrinato) europium derivative

An efficient enzymatic-free electrochemical sensor is firstly developed based on the self-assemblied film of a sandwich mixed (phthalocyaninato) (porphyrinato) europium(III) double-decker complex, Eu(Pc)[T(OH)PP], [Pc = phthalocyaninate, T(OH)PP = 5,10,15,tris (4-tert-butylphenyl)-20-(4-hydroxyphenyl)porphyrinate] prepared by using a solution-processing QLS method. The Eu(Pc)[T(OH)PP]semiconducting active layer on an ITO working electrode leads to a good sensing property for the detection of dopamine with an excellent selectivity, due to the high Eu(Pc)[T(OH)PP] molecular ordering/packing in the QLS film and more favorable interaction between the Eu(Pc)[T(OH)PP] and DA molecules. The amperometric responses are linearly proportional to the concentration of dopamine in the range of 8–100 [Formula: see text]M, with a low detection limit of 4.8 [Formula: see text]M and good sensitivity, indicating the great potential of electroactive tetrapyrrole rare earth sandwich type complexes in the field of nonenzymatic electrochemical sensors.