Stability of Partially Fluorinated Phthalocyanine Monolayers: Influence of Hydrogen Bonding Revisited

Abstract

Hydrogen-like bonding between halogen and hydrogen atoms is widely accepted as the driving force in self-ordering process of various molecular layers. A proper understanding of how the molecular periphery influences the self-ordering is crucial for formation of structurally and electronically well-defined interfaces. To probe the stability of ordered molecular layers of phthalocyanines with various fluorination on the Si(111)-Tl 1 × 1 surface we introduce utilization of a strong electric field of the tip of the scanning tunneling microscope. Ab-initio calculations on extended lattices are used to distinguish molecule–substrate and intermolecular interactions. A systematic comparison of combinations of phthalocyanines with various fluorination provides an understanding of how the molecular periphery influences the intermolecular interaction. We demonstrate that the straightforward explanation of the process of self-ordering by hydrogen-like bonding is not acceptable in the studied case.

Interfaces between Different Iron Phthalocyanines and Au(111): Influence of the Fluorination on Structure and Interfacial Interactions

“…The monolayer structures of metal phthalocyanines on metal surfaces are of interest for a long time; structures depend on the interplay of substrate–molecule and molecule–molecule interactions, − and even small changes in the molecular structure as the exchange of the phthalocyanine central metal atom or the fluorination of the benzene rings can cause structural changes. , In many cases, the fluorination increases the intermolecular distances because of repulsive intermolecular interactions caused by the fluorine atoms, − allowing a tuning of interface properties. We note that more recently also a coadsorption of two different phthalocyanines or porphyrins (among others, with a different degree of fluorination) was investigated with the aim to tune geometric and/or electronic properties. ,,− …”

Modeling of High-Temperature Ordered Structures with Weak Intermolecular C–H···F and C–H···N Bonds

“…Self-assembly of two-dimensional (2D) supramolecular structures driven by the formation of weak C–H···O, C–H···F, , and C–H···N − bonding and their combination with O–H···O bonds has been observed on solid surfaces. C–H···N interactions are known to occur between pyridine derivatives − and other nitrogen-containing molecular building blocks .…”

“…C–H···N interactions are known to occur between pyridine derivatives − and other nitrogen-containing molecular building blocks . C–H···F bonding arises as the primary intermolecular interaction stabilizing molecular networks of partially fluorinated porphyrin and phthalocyanine on solid substrates, but in other cases, it plays a complementary role in addition to stronger HB interactions …”

“…3 The geometrical characteristics of weak HB interactions are rather similar for various pairs of HB donors and acceptors, but they exhibit a less strict directionality in comparison to stronger HBs, such as O−H•••O. 4 Self-assembly of two-dimensional (2D) supramolecular structures driven by the formation of weak C−H•••O, 5 C− H•••F, 6,7 and C−H•••N 8−12 bonding and their combination with O−H•••O bonds 13 has been observed on solid surfaces. C−H•••N interactions are known to occur between pyridine derivatives 8−10 and other nitrogen-containing molecular building blocks.…”

Recent advances in electroanalytical drug detection by porphyrin/phthalocyanine macrocycles: developments and future perspectives

“…27,28 The interest of chemists in the application of phthalocyanines as (bio)electroanalytical sensors is centered on the high stability of the macrocycles, as well as on the formation of thin and stable films on the electrode surface, when compared to a porphyrin system. 29,30 Another fact that can be attributed to the choice of phthalocyanines is the lesser tendency to undergo redox oxidative processes, mainly in the form of metallo-phthalocyanines. 31,32 Similar to the porphyrins that are applied to catalyze reactions on electroanalytical sensors, in phthalocyanines the structural variation is composed of functional groups that can interact strongly with the electrode surface, in covalent or even electrostatic forces.…”