Novel pyridinium inner salt dye and its complexes: synthesis, crystal structures and photophysical properties.

Two novel metal complexes, namely [Tb2(L)6(H2O)4]·(NO3)6·L2·(H2O)18 (1) and [Hg(L)Cl2]n (2), were obtained by the reaction of D-π-A (D = donor, π = conjugated spacer, A = acceptor) type pyridinium inner salt dye, trans-4-[(p-N,N-dimethylamino)styryl]-N-(2-propanoic-acid) pyridinium (L) with corresponding metal salts. Single crystal X-ray diffraction analyses reveal that compound 1 possesses dinuclear motif in which two Tb(III) ions are linked by four carboxylate groups while complex 2 exhibits 1D chain structure based on Hg(II) ions bridged by carboxylate groups. The linear and non-linear optical properties of complexes 1 and 2 have been studied. Both 1 and 2 exhibit intense single-photon excited fluorescence (SPEF) and two-photon excited fluorescence (TPEF) in the red range. Results show that the replacement of central ions from Hg(2+) to Tb(3+) influence the two-photon absorption cross-section significantly through increasing the density of the chromophore. However, the peak positions of two-photon excited fluorescence are only slightly affected. Compared with L molecule, complex 1 shows enhanced two-photon absorption cross-section and decreased fluorescent lifetime.

Special type of distal junctional failure exhibits pelvic incidence changes: sacroiliac joint-related pain following lumbar spine surgery.

Background: Currently, change in pelvic incidence (PI) in patients after spinal surgery have not been associated with clear clinical symptoms. This study sought to compare changes in the sagittal parameters of different patients before and after thoracolumbar spine surgery, the relationship between PI change and sacroiliac joint pain (SIJP) after surgery was clarified, and the correlation between PI change and sacroiliac joint (SIJ) activity was verified. Methods: This study retrospectively analyzed the data of patients who underwent thoracolumbar fusion at Sun Yat-sen Memorial Hospital from January 2019 to June 2021. The spinal and pelvic parameters [including pelvic tilt (PT), sacral slope (SS), PI, lumbar lordosis (LL) angle, etc.] of 409 patients with standard standing lateral radiographs before and after surgery were compared and analyzed. Postoperative follow-up of all patients with standardized SIJP assessment. The incidence of postoperative SIJP, and its correlation with sagittal parameters of the spine and pelvis, surgical methods, and the basic characteristics of patients were analyzed. The Chi-square test was used for categorical variables, the independent-sample t-test was used for generally conformed normally distributed continuous variables. Risk factors associated with the development of SIJP were analyzed using logistics regression. Correlations among SS, PI, and the 4 other sagittal parameters were analyzed using the Pearson correlation coefficient (r). Results: Postoperative PI changes tended to be larger in the lowest instrumented vertebra (LIV) (L4 and above: 1.63°; L5: 2.43°; S1: 3.83°; P<0.05) and longer fixed segment. The risk factors for SIJP included a PI >4° [odds ratio (OR) =13.051; P<0.001], LIV S1 (OR =3.378; P=0.023), and fixed total segment ≥3 (OR =2.632; P=0.038). ∆PI was significantly correlated with ∆SS in patients with non-S1 distal fixation vertebrae (R2=0.388; P<0.01), but no such correlation was found in patients with S1 distal fixation vertebrate. Conclusions: Changes in PI values after thoracolumbar spine surgery can correctly reflect the motion state of the SIJ. Excessive changes in PI (>4°) are similar to the mechanism of distal junctional kyphosis (DJK), while such changes make patients prone to SIJP following lumbar spine surgery.