Multiple Coordination in Porphyrinoid Hybrid: Changing the Delocalization within the Extended π-System

Abstract

π-Extended and strongly coupled chromophores are constantly explored because of their potential for finding a place in many fields of research focusing on both aspects – the fundamental knowledge and the application studies. The synthetic approach leading to controlled formation of porphyrinoid system with two coordination cores shows an alternative way for controlling the delocalization within the extended π-system. It drastically influences the optic response which after a basic initiator (reversibly) shifts the absorbance to the red region following the significant planarization that increases observed communication between two subunits. Even deeper modification can be done within the system by doping the obtained structure with boron(III) that in addition introduces another switching factor based on Lewis acidity of the introduced metalloid.

(Aza)Acenes Share the C2 Bridge with (Anti)Aromatic Macrocycles: Local vs. Global Delocalization Paths

“…Thel ocal contributors are significantly marked in two electron reduced structures 8x and confirmed by the recorded emission(s) at l max comparable to 6x. [7,8,19,25] Thelack of local of emission in boron(III) complexes 9a/9b is consistent with acontribution of paratropic current.…”

“…Thee xtension of the p-cloud in conjugated systems significantly influence the UV/Vis absorption as documented for PA Hs (e.g. ( aza)acenes) [3] or macrocycles [5][6][7][8] including triphyrins(2.1.1). [14,15] TheU V/Vis spectra of 7a and 7c ( Figure 3A)w ith intense Soret bands (l = 434 nm and l = 421 nm, respectively) accompanied by as et of Q-bands with the most red-shifted band at l = 662 nm (7a)and l = 588 nm (7c)( Figure 3A)s how the picture consistent with the significant contribution of globally extended delocalization involving both subunits of the hybrid systems and characteristic for aromatic porphyrinoids.…”

“…Actually the range of chemical shifts (d)i s an intuitive tool helpful in assessing the contribution of ag lobal and local diatropic p-expansion that de-shields the perimeter lines shifting them down-field. [7,8,19] At ypical behavior of the paratropic current is the up-field relocation of the margin resonances. [15,18,20] Thel ack of global effect either diatropic or paratropic will leave the influence of local conjugation characteristic for unsaturated carbocycles or heterocycles.Thus,itisexpected that changes in the character of analyzed molecules and being ac onsequence of switching from diatropic to paratropic current will significantly influence the observed d range.T he observed chemical shifts of naphthalene subunit in 7a (d = 9.94 ppm (1 1 ,2 1 ), d = 8.59 ppm (1 3 ,2 3 ), d = 8.10 ppm (1 4 ,2 4 )) show an oticeable down-field shift while comparing to 6a (d = 7.92 ppm (1 1 ,2 1 ), d = 7.79 ppm (1 3 ,2 3 ), d = 7.44 ppm (1 4 ,2 4 )) consistently with efficient global delocalization and significant contribution of 22p electrons path ( Figure 4A,B, green arrow).…”

“…A modulation of delocalization in structures merging acenes and macrocycles can be also realized by a controlled linking of isolated motifs [7] simultaneously masking a specific behavior that after revealing via a fundamental process (e.g. redox) [8] strongly influence final response changing the observed π‐delocalization path (e.g.…”

(Aza)Acenes Share the C2 Bridge with (Anti)Aromatic Macrocycles: Local vs. Global Delocalization Paths

“…The extension of the π‐cloud in conjugated systems significantly influence the UV/Vis absorption as documented for PAHs (e.g. (aza)acenes) [3] or macrocycles [5–8] including triphyrins(2.1.1) [14, 15] . The UV/Vis spectra of 7 a and 7 c (Figure 3 A) with intense Soret bands ( λ =434 nm and λ =421 nm, respectively) accompanied by a set of Q‐bands with the most red‐shifted band at λ =662 nm ( 7 a ) and λ =588 nm ( 7 c ) (Figure 3 A) show the picture consistent with the significant contribution of globally extended delocalization involving both subunits of the hybrid systems and characteristic for aromatic porphyrinoids [13, 15] .…”