Supramolecuar Motifs in s-Block Metal-Bound Sulfonated Monoazo Dyes:  The Case of Orange G

Abstract

Solid-state structures of Mg, Sr, Ba, Na2, Na0.8K1.2, NaRb, and Na1.5Cs0.5 complexes of the disulfonated dye 7-hydroxy-8-(phenylazo)-1,3-naphthalenedisulfonic acid, Orange G, are presented. It is shown that the s-block metal salts of the Orange G dianion (Og) can be categorized into three structural classes related to those previously proposed for simple monosulfonated azo dyes. All of the structures feature alternate organic/inorganic layering, but whereas the Mg, Ca, and Li complexes are solvent-separated ion-pair species, the Sr and Ba complexes form simple discrete molecules based on metal-sulfonate bonding, and the heavy alkali metal complexes utilize a variety of M-O interactions to form 2- and 3-dimensional coordination networks. These structural differences are rationalized in terms of simple properties of the metals (charge, size, and electronegativity) and the steric demands of the arylsulfonate groups. The Ag2 complex of Orange G is also structurally characterized, and in contrast to the s-block salts, it is found to exhibit strong Ag pi bonds. In confirmation of the above, the crystal structures of [Mg(H2O)6][Og] . 3.33H2O, [Sr(Og)(H2O)7].H2O, [Ba(Og)(H2O)7]2 . 2H2O, [Na2(Og)(H2O)6.67], [Na2(Og)(H2O)2(HOEt)], [Na0.8K1.2(Og)(H2O)6] . 1.75H2O, [NaRb(Og)(H2O)6.5] . 2.375H2O, [Na1.5Cs0.5(Og)(H2O)6] . 0.5H2O, and [Ag2(Og)(H2O)4].H2O are presented.

Coordination polymer networks with s-block metal ions

“…One difficulty in examining sulfonated dyes is that they exhibit generally poor crystal growth properties, mak- ing single-crystal diffraction studies difficult. An exception is the disulfonated naphthalene-based dye Orange G, 7-hydroxy-8-(phenylazo)-1,3-naphthalenedisulfonic acid, the salts of which are found to grow as robust crystals [29]. The s-block metal salts of the Orange G dianion (Og) can be categorized into three structural classes related to those previously proposed for simple monosulfonated azo dyes.…”

Supramolecular Structure in s‐Block Metal Complexes of Sulfonated Monoazo Dyes: Discrepant Packing and Bonding Behavior of ortho‐Sulfonated Azo Dyes

“…Specifically, compounds of meta ‐sulfonated azo dyes differed from their para equivalents in that Ca as well as Mg species were found to form solvent‐separated ion‐pair solids. The disulfonated dye 7‐hydroxy‐8‐(phenylazo)‐1,3‐naphthalenedisulfonic acid (Orange G), was also examined 4. A further extension of those metals forming solvent‐separated ion‐pair solids was observed, with Mg, Ca, and Li all doing so with Orange G 4.…”

“…The disulfonated dye 7‐hydroxy‐8‐(phenylazo)‐1,3‐naphthalenedisulfonic acid (Orange G), was also examined 4. A further extension of those metals forming solvent‐separated ion‐pair solids was observed, with Mg, Ca, and Li all doing so with Orange G 4. 5 These changes can be related to the electronegativity of the metal, which can in turn be treated as an expression of the “ionic character” of the metal.…”

“…An obvious omission from previous work1, 4, 6 is the category of ortho‐ sulfonated azo dyes. Despite being common in commercial colorants, these were omitted from discussion in reference 1.…”

Influence of Metal Cations and Coordination Modes on Luminescent Group 1 and 2 Metal Sulfonate Complexes Constructed from 4,4′‐Dihydroxybiphenyl‐3,3′‐disulfonic Acid

“…[11] Moreover, the sulfonate group is usually considered to be a weak ligand, as is often evidenced by its inability to replace water molecules from the primary coordination spheres of many metal ions; in many cases, it is only involved in hydrogen-bonding supramolecular networks.…”