Tetraalkylammonium bromide is produced in situ. The effect of the length of bromoalkyl chains is recognized, indicating the importance of side-chain engineering. The hydrogen evolution rate is improved significantly by the presence of Pd.

Conjugated length and dispersity are modulated by the incorporation of nonconjugated groups. The integration of 1,4-butanediylbis(oxy) groups into poly[(1,-4-benzo{2,1,3}thiadiazole)-co-1,4-benzene] gives numerous co-polymers. The presence of the 1,4-butanediylbis(oxy) unit in the polymer backbone interrupts the conjugation length. The optical energy gap is not much affected. The variation in the hydrogen evolution rate (HER) is evident. Density-functional-theory calculations suggest that the distribution of residual Pd along the polymer chain could be influenced considerably by the introduction of 1,4-butanediylbis(oxy) group, accounting for the variation in the HER. On the other hand, a macromonomer with oligo tert-butyl acrylate side chains synthesized through atom transfer radical polymerization is copolymerized with 3,7-dibromo-dibenzothiophene 5,5-dioxide to furnish a random copolymer. The ester groups in the polymer can be transformed to the acid moieties. The polymer with the acid functionality exhibits superior dispersity in the reaction solvents. Nonetheless, the difference in the hydrogenevolution activity is marginal between the two polymers, revealing that the increase in the polymer dispersity does not essentially improve the photoactivity for this reaction. These studies reveal that a structural variation could simultaneously lead to the alternation in numerous properties. Emphasis on a particular property could be misleading in designing active photocatalysts in hydrogen evolution.

Palladium‐catalyzed direct‐arylation (DAr) has shown promise in synthesizing conjugated molecules and polymers. Herein, palladium‐catalyzed DAr reactions of 2‐bromo‐3‐alkyl‐thiophene in the presence of distinct bases including pivalate, acetate, carbonate, and hydroxide, are performed in vitro and in silico. The entire pathways comprising oxidative addition (OA), concerted metalation‐deprotonation (CMD), and reductive elimination (RE) are investigated theoretically, indicating that the rate‐determining step varies with the base. Natural bond orbital analysis on the CMD transition states reveals that the classical Lewis pair and frustrated Lewis pair play important roles in the base‐coordinated CMD and the base‐assisted CMD, respectively. Multivariate regression analysis between the calculated CMD activation barrier and the orbital interactions yields a model equation, which is employed to further elucidate the characters of Lewis acid and Lewis base in the CMD. Overall, the computational results from the present study are in agreement with the experimental reaction yields and constitute the interpretation of the working principles for the DAr catalytic system, shedding light on further optimization and advance.