Designing Optical Anisotropy: Silver-Aminoalkylpyridine Nitrate Complexes with Tunable Structures

초록

To introduce a design strategy for improving optical properties, two silver-amino alkylpyridine nitrate complexes, AgC6H8N3O3 and Ag(2)C(14)H(2)0N(6)O(6), were successfully synthesized using a recrystallization method. By employing polarizable pi-conjugated [NO3-] ions, two types of pyridine ligands, and silver cations with a high affinity for pyridine, we obtained a one-dimensional chain structure with 4-aminomethylpyridine (AgC6H8N3O3) and a zero-dimensional molecular compound by introducing a relatively flexible aliphatic chain with 4-(2-aminoethyl)-pyridine (Ag(2)C(14)H(2)0N(6)O(6)). The compounds crystallize in the triclinic crystal system with the centrosymmetric P-1 space group, exhibiting a change in orientation between the pi-conjugated system and the silver ion. Despite similar optical band gaps (3.69 eV for AgC6H8N3O3 and 3.73 eV for Ag(2)C(14)H(2)0N(6)O(6)), AgC6H8N3O3 shows higher absorption in the 350-600 nm range. Electronic structure calculations support the ultraviolet absorption findings, suggesting that charge transfer with pi-conjugated systems influences birefringence. Ag(2)C(14)H(2)0N(6)O(6)exhibits experimental birefringence (0.261@546.1 nm) surpassing that of AgC6H8N3O3 (0.212@546.1 nm), placing it among the highest recorded values within metal-pyridine incorporating nitrate complexes. The nonconventional orientation of pi-conjugated [NO3-] ions contributes to this phenomenon, enhancing the action of free pi-conjugated orbitals. This design strategy for micromodulating the alignment of the pi-conjugated system promises to be an effective approach for enhancing optical properties, such as birefringence.

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