Four bis-ammonia ligated cobalt corroles and four mono-DMSO ligated cobalt corroles with different meso-aryl substituents on the macrocycle (A 2 B-and A 3 -corroles) were synthesized and investigated as to their electrochemical and spectroscopic properties under different solution conditions. The complexation energies of the investigated cobalt corroles were [a] Scheme 2. Structures of the investigated bis-ammonia and mono-DMSO meso-aryl cobalt corroles. dinated form of A 3 -and/or A 2 B-cobalt corroles) which will bind CO. Very recently, concentrations of CO as low as a few hundred ppb were measured by SAW sensors emphasizing the interest of such sensors for the detection of carbon monoxide. [4] Scheme 3. Synthesis of mono-DMSO and bis-NH 3 cobalt corroles.The eight cobalt corroles 1DMSO-4DMSO and 1NH 3 -4NH 3 were prepared according to the synthetic procedure shown in Scheme 3. The A 3 -and A 2 B-free-base corroles 1H-4H were synthesized according to published procedures described by Gryko and co-workers, [5] and metallated with Co(OAc) 2 in DMSO to give the cobalt complexes 1DMSO-4DMSO, each with a single DMSO molecule as axial ligand. These mono-DMSO adducts were then treated with an aqueous ammonia solution to give the bis-ammonia derivatives 1NH 3 -4NH 3 in 79-94 % yield. Spectroscopic Characterization1DMSO-4DMSO were measured at a concentration of 10 -3 M in both CH 2 Cl 2 and DMSO containing 0.1 M TBAP (Figure 2). In CH 2 Cl 2 the spectra are characterized by a Soret band at 379-387 nm and a single less intense band at 562-566 nm. There is also a shoulder on the Soret band at about 414-417 nm. These spectra are similar to previously reported UV/Vis spectra for a related series of mono-DMSO ligated cobalt nitrophenylcorroles under the same solution conditions. [3] Similar spectral patterns are seen for 2DMSO, 3DMSO and 4DMSO in the two solvents but this is not the case for 1DMSO as seen in Figure 2. The spectrum in CH 2 Cl 2 (Figure 2a) is assigned to the mono-DMSO adduct while in DMSO a mixture of the five-and six-coordinate derivatives are proposed to exist, the hexa-coordinate DMSO adduct having bands at 417, 442, 453 and 618 nm as described on the following pages. It should be noted that 1DMSO is the only cobalt corrole among the currently investigated compounds which possesses six electronwithdrawing substituents on the meso-phenyl rings, and this seems to facilitate the binding of a second DMSO molecule to the cobalt center of the neutral compound. Stronger pyridine binding constants were also earlier reported for cobalt corroles with electron-withdrawing substituents on the meso-phenyl rings. [3] UV/Visible spectra of the bis-ammonia complexes 1NH 3 -4NH 3 were also measured at a concentration of 1 × 10 -3 M un-Eur.(CO 2 MePh)Mes 2 CorCo(DMSO) (2DMSO): 88 % yield (211 mg). UV/ Visible (toluene, 1 % DMSO): λ max (ε × 10 -3 L·mol -1 cm -1 ) 383 (62.9), 563 (13.1) nm. 1 H NMR [500 MHz, CDCl 3 + NH 3 (g)]: δ = 8.98 (d,
In this research, Surface Acoustic Wave (SAW) sensors are combined with a cascade impactor to perform real time PM10 and PM2.5 mass concentration measurements. The SAW sensors consist of 125 MHz delay lines based on Love waves propagating on an AT-cut quartz substrate. The Love waves are guided on the substrate’s surface using a silica layer. SAW sensors themselves are not capable to discriminate particles by their size, therefore, particle separation based on aerodynamic diameter is achieved using a 3 Lpm dedicated cascade impactor. The latter was designed to integrate the SAW sensors which are monitored using a phase shift measurement. The collected particles impact on the acoustic sensor’s surface inducing a gravimetric effect that modifies the acoustic wave propagation conditions. The resulted phase shift allows the measurement of the mass deposited on the sensitive zone. The novel cascade impactor with SAW sensors as particle collecting stages is exposed to different aerosols in the 0–150 μg/m3 concentration range and proved to be able to detect and differentiate particles based on their size in real time. The system’s response was compared to a commercial optical counter based on light scattering technology and was found to be in good agreement with it.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.