Crystal structure, phase transition, electrical and optical properties of p-hydroxypyridinium iodate [C5H6NO (IO3)]2

[o‐C5H4NHOH]2[I7O18(OH)]⋅3 H2O: An Organic–Inorganic Hybrid SHG Material Featuring an [I7O18(OH)] Branched Polyiodate Chain

“…The presence of strong electron donor or acceptor groups causes a splitting of the intense shorter wavelength band [35] . The experimental band gap of I is 3.90 eV, which is much wider than those of the other organic–inorganic hybrid iodates reported, for example 3.77 eV for ( p ‐C 5 H 4 NHOH)(IO 3 ) [31, 36] . Moreover, its band gap is also larger than many of inorganic iodates such as CsVO 2 F(IO 3 ) (2.39 eV) [37] and Nb 2 O 3 (IO 3 ) 2 (SO 4 ) (3.25 eV) [38] .…”

“…[35] The experimental band gap of I is 3.90 eV, which is much wider than those of the other organicinorganic hybrid iodates reported, for example 3.77 eV for (p-C 5 H 4 NHOH)(IO 3 ). [31,36] Moreover, its band gap is also larger than many of inorganic iodates such as CsVO 2 F(IO 3 ) (2.39 eV) [37] and Nb 2 O 3 (IO 3 ) 2 (SO 4 ) (3.25 eV). [38] Under the excitation at 380 nm, I displays a broad emission band maximizing at 428 nm and being weaker than o-C 5 H 5 NO, which indicates the fluorescence effect of I is originated from o-C 5 H 5 NO and I is able to emit purple fluorescence at room temperature (Figure S5).…”

“…In addition, several simple amine based iodates were reported, and usually hydrogen bonds are present in these compounds, such as (C 6 H 20 N 3 )(IO 3 ) 3 ⋅2 H 2 O, [28] and (C 6 H 16 N 4 O 2 )(IO 3 ) 2 [29] . Several organic–inorganic hybrid iodates with NCS structures have been reported including Cu 2 (IO 3 ) 3 (2, 2′‐bipy) 2 ⋅1.5 Cl⋅0.5 H 3 O⋅4 H 2 O⋅0.19I 2 [30] and ( p ‐C 5 H 4 NHOH)(IO 3 ), [31] but their SHG properties had not been studied. Thus, it is still a great challenge to design and synthesize organic–inorganic hybrid polyiodates with NCS structures and large SHG effects.…”

“…The N−H stretching modes occur at lower frequencies as the hydrogen bonds of N−H are weaker than O−H. The bands at 2806 and 2710 cm −1 , at 1430 and 1421 cm −1 , at 519 and 473 cm −1 are assigned to N‐H vibrations [31] . The C−O bonds are strengthened since O−H bonds are impaired by hydrogen bonding.…”

“…The bands at 2806 and 2710 cm À1 , at 1430 and 1421 cm À1 , at 519 and 473 cm À1 are assigned to N-H vibrations. [31] The C À O bonds are strengthened since O À H bonds are impaired by hydrogen bonding. The bands at 1350 cm À1 , at 473 and 411 cm À1 can be assigned to the CÀO vibrations.…”