Abstract
Our present study provides expedient methods for the synthesis of novel substituted indanes, pyrido[3,2,1-
jk]carbazoles and pyrido[3,2,1-kl]phenothiazines utilizing intramolecular Friedel-Crafts cyclialkylations of
synthesized heteroaryl alcohols. This methodology is realized by a three-step protocol involving first
esterification of starting carboxylic acids to the corresponding esters, addition of Grignard reagents to give
carbinol precursors and followed by Friedel-Crafts cyclizations of alcohols mediated by AlCl3/CH3NO2, PPA or
P2O5-catalysts to furnish the desired polycycles in good to excellent yields of 65-85%. The designed protocol
offers easy access to the pharmaceutically promising templates in good yields. The molecular structural
elucidations of all newly obtained compounds have been proved by spectral and elemental analysis.

Background: Cobalt oxide nanocubes have garnered significant attention as potential supercapacitor electrodes due to their unique structural and electrochemical properties. The spent lithium-ion batteries (LiBs) are considered as zero-cost source for cobalt oxide production.

Objectives: The aim of this work is to recover cobalt oxide from spent LiBs and study its electrochemical performance as a supercapacitor electrode material.

Methods: This study uses an electrodeposition method to obtain cobalt oxide honeycomb-like anodes coated on Ni foam substrates from spent Li-ion batteries for supercapacitors applications. The effect of annealing temperature on the cobalt oxide anode has been carefully investigated; 450ºC annealing temperature results in nanocubes on the surface of the cobalt oxide electrode. X-ray diffraction confirmed the formation of the Co_-3O_-4-NiO electrode.

Results: The Co₃O₄-NiO nanocubes electrode has shown a high specific capacitance of 1400 F g^-1 at 1 A g^-1 and high capacitance retention of ~96 % after 2250 cycles at a constant current density of 10 A g^-1 compared to 900 F g^-1 at 1 A g^-1 as for prepared Co3O4 honeycomb.

Conclusion: This strategy proves that the paramount importance of Co₃O₄-NiO nanocubes, meticulously synthesized at elevated temperatures, as a supremely effective active material upon deposition onto transition metal foam current collectors, establishing their indispensability for supercapacitor applications.